Some hardware manufacturers have created devices which are compatible with MS-DOS and Windows 95/98 only. They seem to emulate part of the normally available hardware in the devices by software packages sold together with the device. Specification on these devices are not presented to the world so it is almost impossible to write drivers for these devices. Below a list of devices reported as being Linux incompatible will be given.
Simply put, it is best to avoid hardware which states things like "Needs Windows" or "Windows only".
Brother HL-820 printer
Canon LBP-465 printer
HP Deskjet 710, 720, 820 and 1000 series printers (although Windows only) are supported under Linux. Have a look at here. Be warned: Support is still in early development.
Lexmark 1000 inkjet printer
Lexmark 3200. For windows it has a emulation driver for HP500 and HP500C. Under Linux this printer will not work using a HP500 or HP500C driver.
Lexmark 5000 printer
Lexmark CJ5000 (ColorJet) printer
OkiData OkiPage 4w
Sharp JX-9210 printer
3Com 3CXM356/3CCM356 and 3CXM656/3CCM656 PCMCIA
AOpen FM56-P and FM56-H
Boca Research 28.8 internal modem (model MV34AI)
Boca Research 33.6 internal modem (model MV34)(Joe Harjung has succeeded in configuring the modem under Win95 and then soft booting into Linux with the modem still working. Filippo is using this modem under Linux directly without any problems and without soft booting from Windows. I definitely need more info on these Boca Research modems.) The Boca Research 33.6 modem (model M336I) is mentioned to work with Linux. The only thing that needed to be done was diabling Plug and Play. Here are the specs of the modem
Three stickers saying "MC2920A-3.3", "E6030D 4035-01" and "1721 8011 A"
Chips etc on the board
Cirrus Logic CL-MD3450D-SC-B
Cirrus Logic MD1724-11VC-D
Omron G5V-1 (2 of them)
AST (?) M628032-20E1
Cirrus Logic CL-MD4450C-SC-A
two empty places for additional chips, one of which might be a Cirrus Logic CL-MD1724D
4 jumpers for COM port selection
10 jumpers for IRQ selection
other unknown jumpers
Compaq 192 PCMCIA modem/serial card
HP Fastmodem D4810B
IBM Mwave ("Dolphin") card. This card is a combination of sound, modem, fax, voice control and dictation. Software is replacing part of hardware functionality so this software should be loaded to get things working.
Multiwave Innovation CommWave V.34 modem ( here)
Megahertz XJ/CC2560 PCMCIA
New Media Winsurfer PCMCIA modem/serial card
US Robotics WinModem series
Zoltrix 33.6 Win HSP Voice/Speaker Phone modem
Zoltrix Phantom 56K, model FM-HSP56PCI, chipset PCTel (PCI)