I have now worked out that the 3c59x driver has not changed, but I don't know what has!. Here is an lspci -v from Knoppix 3.3 and 3.4. Knoppix 3.3 initialises the card correctly (3Com Corporation 3c556B Hurricane CardBus) and I get an IP adress from the dhcp server. However the card is not detected correctly in Knoppix 3.4 (3Com Corporation 3c556B CardBus [Tornado]).
Dallas

From Knoppix 3.3....
00:00.0 Host bridge: Intel Corp. 440BX/ZX/DX - 82443BX/ZX/DX Host bridge (rev 03)
Flags: bus master, medium devsel, latency 64
Memory at f8000000 (32-bit, prefetchable) [size=64M]
Capabilities: [a0] AGP version 1.0

00:01.0 PCI bridge: Intel Corp. 440BX/ZX/DX - 82443BX/ZX/DX AGP bridge (rev 03) (prog-if 00 [Normal decode])
Flags: bus master, 66Mhz, medium devsel, latency 128
Bus: primary=00, secondary=01, subordinate=01, sec-latency=64
I/O behind bridge: 00003000-00003fff
Memory behind bridge: f4200000-f5ffffff

00:02.0 CardBus bridge: Texas Instruments PCI1450 (rev 03)
Subsystem: IBM: Unknown device 0130
Flags: bus master, medium devsel, latency 168, IRQ 11
Memory at 50000000 (32-bit, non-prefetchable) [size=4K]
Bus: primary=00, secondary=02, subordinate=04, sec-latency=176
Memory window 0: 10000000-103ff000 (prefetchable)
Memory window 1: 10400000-107ff000
I/O window 0: 00004000-000040ff
I/O window 1: 00004400-000044ff
16-bit legacy interface ports at 0001

00:02.1 CardBus bridge: Texas Instruments PCI1450 (rev 03)
Subsystem: IBM: Unknown device 0130
Flags: bus master, medium devsel, latency 168, IRQ 11
Memory at 50100000 (32-bit, non-prefetchable) [size=4K]
Bus: primary=00, secondary=05, subordinate=07, sec-latency=176
Memory window 0: 10800000-10bff000 (prefetchable)
Memory window 1: 10c00000-10fff000
I/O window 0: 00004800-000048ff
I/O window 1: 00004c00-00004cff
16-bit legacy interface ports at 0001

00:03.0 Ethernet controller: 3Com Corporation 3c556B Hurricane CardBus (rev 20)
Subsystem: 3Com Corporation: Unknown device 6356
Flags: bus master, medium devsel, latency 80, IRQ 11
I/O ports at 1800 [size=256]
Memory at f4101400 (32-bit, non-prefetchable) [size=128]
Memory at f4101000 (32-bit, non-prefetchable) [size=128]
Expansion ROM at <unassigned> [disabled] [size=128K]
Capabilities: [50] Power Management version 2

00:03.1 Communication controller: 3Com Corporation Mini PCI 56k Winmodem (rev 20)
Subsystem: 3Com Corporation: Unknown device 6159
Flags: medium devsel, IRQ 11
I/O ports at 2000 [size=256]
Memory at f4101c00 (32-bit, non-prefetchable) [size=256]
Memory at f4101800 (32-bit, non-prefetchable) [size=128]
Capabilities: [50] Power Management version 2

00:05.0 Multimedia audio controller: Cirrus Logic CS 4614/22/24 [CrystalClear SoundFusion Audio Accelerator] (rev 01)
Subsystem: IBM: Unknown device 0153
Flags: bus master, slow devsel, latency 64, IRQ 11
Memory at f4100000 (32-bit, non-prefetchable) [size=4K]
Memory at f4000000 (32-bit, non-prefetchable) [size=1M]
Capabilities: [40] Power Management version 2

00:07.0 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ISA (rev 02)
Flags: bus master, medium devsel, latency 0

00:07.1 IDE interface: Intel Corp. 82371AB/EB/MB PIIX4 IDE (rev 01) (prog-if 80 [Master])
Flags: bus master, medium devsel, latency 64
I/O ports at 1c00 [size=16]

00:07.2 USB Controller: Intel Corp. 82371AB/EB/MB PIIX4 USB (rev 01) (prog-if 00 [UHCI])
Flags: bus master, medium devsel, latency 64, IRQ 11
I/O ports at 1c20 [size=32]

00:07.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 03)
Flags: medium devsel, IRQ 9

01:00.0 VGA compatible controller: ATI Technologies Inc Rage Mobility P/M AGP 2x (rev 64) (prog-if 00 [VGA])
Subsystem: IBM ThinkPad A20m
Flags: bus master, stepping, medium devsel, latency 66, IRQ 11
Memory at f5000000 (32-bit, non-prefetchable) [size=16M]
I/O ports at 3000 [size=256]
Memory at f4200000 (32-bit, non-prefetchable) [size=4K]
Expansion ROM at <unassigned> [disabled] [size=128K]
Capabilities: [50] AGP version 1.0
Capabilities: [5c] Power Management version 1

From Knoppix 3.4...

0000:00:00.0 Host bridge: Intel Corp. 440BX/ZX/DX - 82443BX/ZX/DX Host bridge (rev 03)
Flags: bus master, medium devsel, latency 64
Memory at f8000000 (32-bit, prefetchable) [size=64M]
Capabilities: [a0] AGP version 1.0

0000:00:01.0 PCI bridge: Intel Corp. 440BX/ZX/DX - 82443BX/ZX/DX AGP bridge (rev 03) (prog-if 00 [Normal decode])
Flags: bus master, 66MHz, medium devsel, latency 128
Bus: primary=00, secondary=01, subordinate=01, sec-latency=64
I/O behind bridge: 00003000-00003fff
Memory behind bridge: f4200000-f5ffffff

0000:00:02.0 CardBus bridge: Texas Instruments PCI1450 (rev 03)
Subsystem: IBM: Unknown device 0130
Flags: bus master, medium devsel, latency 168, IRQ 11
Memory at 50000000 (32-bit, non-prefetchable) [size=4K]
Bus: primary=00, secondary=02, subordinate=04, sec-latency=176
Memory window 0: 10400000-107ff000 (prefetchable)
Memory window 1: 10800000-10bff000
I/O window 0: 00004000-000040ff
I/O window 1: 00004400-000044ff
16-bit legacy interface ports at 0001

0000:00:02.1 CardBus bridge: Texas Instruments PCI1450 (rev 03)
Subsystem: IBM: Unknown device 0130
Flags: bus master, medium devsel, latency 168, IRQ 11
Memory at 50100000 (32-bit, non-prefetchable) [size=4K]
Bus: primary=00, secondary=05, subordinate=07, sec-latency=176
Memory window 0: 10c00000-10fff000 (prefetchable)
Memory window 1: 11000000-113ff000
I/O window 0: 00004800-000048ff
I/O window 1: 00004c00-00004cff
16-bit legacy interface ports at 0001

0000:00:03.0 Ethernet controller: 3Com Corporation 3c556B CardBus [Tornado] (rev 20)
Subsystem: 3Com Corporation: Unknown device 6356
Flags: bus master, medium devsel, latency 64, IRQ 11
I/O ports at 1400 [size=256]
[virtual] Memory at 10000000 (32-bit, non-prefetchable) [size=128]
[virtual] Memory at 10000080 (32-bit, non-prefetchable) [size=128]
Expansion ROM at <unassigned> [disabled] [size=128K]
Capabilities: [50] Power Management version 2

0000:00:03.1 Communication controller: 3Com Corporation Mini PCI 56k Winmodem (rev 20)
Subsystem: 3Com Corporation: Unknown device 6159
Flags: medium devsel, IRQ 11
I/O ports at 2000 [size=256]
Memory at f4101c00 (32-bit, non-prefetchable) [size=256]
Memory at f4101800 (32-bit, non-prefetchable) [size=128]
Capabilities: [50] Power Management version 2

0000:00:05.0 Multimedia audio controller: Cirrus Logic CS 4614/22/24 [CrystalClear SoundFusion Audio Accelerator] (rev 01)
Subsystem: IBM: Unknown device 0153
Flags: bus master, slow devsel, latency 64, IRQ 11
Memory at f4100000 (32-bit, non-prefetchable) [size=4K]
Memory at f4000000 (32-bit, non-prefetchable) [size=1M]
Capabilities: [40] Power Management version 2

0000:00:07.0 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ISA (rev 02)
Flags: bus master, medium devsel, latency 0

0000:00:07.1 IDE interface: Intel Corp. 82371AB/EB/MB PIIX4 IDE (rev 01) (prog-if 80 [Master])
Flags: bus master, medium devsel, latency 64
I/O ports at 1c00 [size=16]

0000:00:07.2 USB Controller: Intel Corp. 82371AB/EB/MB PIIX4 USB (rev 01) (prog-if 00 [UHCI])
Flags: bus master, medium devsel, latency 64, IRQ 11
I/O ports at 1c20 [size=32]

0000:00:07.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 03)
Flags: medium devsel, IRQ 9

0000:01:00.0 VGA compatible controller: ATI Technologies Inc Rage Mobility P/M AGP 2x (rev 64) (prog-if 00 [VGA])
Subsystem: IBM ThinkPad A20m
Flags: bus master, stepping, medium devsel, latency 66, IRQ 11
Memory at f5000000 (32-bit, non-prefetchable) [size=16M]
I/O ports at 3000 [size=256]
Memory at f4200000 (32-bit, non-prefetchable) [size=4K]
Expansion ROM at <unassigned> [disabled] [size=128K]
Capabilities: [50] AGP version 1.0
Capabilities: [5c] Power Management version 1