Check out this thread:
http://www.knoppix.net/forum/viewtopic.php?t=1573#7172
~rock
I have a second video card installed in a PCI slot (ATI's All-in-Wonder RAGE 12. I have a dual boot system with Windows XP and a Knoppix install of LINUX, running KDE as my default desktop environment.
In windows I have my desktop extended onto a second monitor. Can anyone tell me how to pull this off in KDE (and maybe some other environments)?
Keep in mind that although I'm very familiar with Windows/DOS/PCs, I'm still very much a newbie in Linux.
Check out this thread:
http://www.knoppix.net/forum/viewtopic.php?t=1573#7172
~rock
Boy the last post in that thread really did the trick. Thanks, RockMumbles.

GIGABYTE A520M DS3H AC AMD AM4 Motherboard mATX
$59.99
GIGABYTE Z790 AORUS ELITE AX LGA 1700 Intel Z790 ATX Motherboard with DDR5
$189.99
Intel H310 LGA1151 8-9th Gen DDR4 M.2 NVMe mATX Motherboard IO Shield Battery
$54.99
ASUS PRIME Z490-V Motherboard Intel Z490 10th gen DDR4 LGA 1200 ATX w/ IO Shield
$84.99
GIGABYTE B365 HD3 LGA1151 Intel 9th Gen motherboard
$59.99
Intel H81 Motherboard M.2 NVMe LGA 1150 mATX w/ IO Shield (Random Slot Color)
$29.90
ASUS PRIME B360M-C MicroATX Intel LGA1151 DDR4 HDMI VGA USB RJ-45 Audio
$34.99
ASUS PRIME Z370-A II LGA 1151 Intel Z370 DDR4 DIMM USB3.1 DVI ATX RGB
$69.99
Compo MSI B150I GAMING PRO AC LGA1151 16 Gb DDR4 + Cpu I7 6700+I/O Shields.
$159.00
ASRock Z370 Pro4 LGA 1151 Z370 HDMI USB 3.1 2 Ultra M.2 DDR4 ATX Motherboard
$75.00