First of all, thanks a lot for your feedback!
But I'm not able to get IP (DHCP failure) yet.
Both with encryption enabled and disabled pump -i wlan0 fails.
Below you can find related iwconfig and ipconfig printout commands.

# iwconfig
lo no wireless extensions.

eth0 no wireless extensions.

wmaster0 no wireless extensions.

wlan0 IEEE 802.11g ESSID:"my_ESSID"
Mode:Managed Frequency:2.412 GHz Access Point: xxx
Bit Rate=54 Mb/s Tx-Power=27 dBm
Retry min limit:7 RTS thrff Fragment thr=2346 B
Encryption keyff
Link Quality=68/100 Signal level=-65 dBm Noise level=-127 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

# ifconfig wlan0 up

# ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:18 errors:0 dropped:0 overruns:0 frame:0
TX packets:18 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:900 (900.0 B) TX bytes:900 (900.0 B)

wlan0 Link encap:Ethernet HWaddr 00:13:02:3d:a5:6c
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:20 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:4032 (3.9 KiB)

wmaster0 Link encap:UNSPEC HWaddr yyy
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

# pump -i wlan0
Operation failed.

With encryption disabled I tried to use ndiswrapper as suggested.
Windows drivers for my card should be:
oem11.inf
w39n51.sys

# ndiswrapper -i /oem11.inf
installing oem11 ...
# ndiswrapper -l
oem11 : driver installed
device (8086:4222) present (alternate driver: iwl3945)
# modprobe ndiswrapper
# lsmod | grep ndiswrapper
ndiswrapper 200900 0


# pump -i wlan0
Operation failed.

I tried also to remove iwl3945 before ndiwrapping but result was
that my PC was completely stuck after ndiswrapper.

# lsmod | grep 45
iwl3945 95080 0
mac80211 133388 1 iwl3945
firmware_class 13824 2 iwl3945,pcmcia

Could be a firmware matter? What else?