hi there..
I've got that list of modem (you can use that for windows/linux)

#Most of external modem can be use for linux modem..but here I've got that list:
-US ROBOTIC model 0839-09,ACTIONTEC model EXT560612-01CW,BEST DATA model 565X,SUPRA EXPRESS model 56E,ZOOM model 3049L,3COM/USR model 5686-03 or model 5605-00,CREATIVE FLASH 56 II model DE 5620,VIKING model RFM56KEXT.
# For internal modem:
-ISA MODEM; CREATIVE ISA model DI 5601,SUPRA EXPRESS ISA model 561 SP,BEST DATA ISA model 565P,VIKING PNP-ONLY model RFM 336INC,3COM/usr ISA model 5687-03,ACTIONTEC model 56010-01.US ROBOTIC model 3CP56010-01(PCI MODEM),ACTIONTEC PCI model PCI56012-01CW(PCI modem),ACTIONTEC PC CARD model MDV9012-01(PCMIA modem),ZOOM model 2975 (PCMIA modem).
If you wanna easy one... pick external modem ( most of external modem working for linux... but not all of them ..so be wise to pick modem otherwise you will get headache..)

I hope this helps..

Cheerss