Looks like google knows tons about this issue!

Here's a reference of refrences:

http://www.ntlug.org/~cbbrowne/linuxhardware.html

ALL winmodems will break at some time in the future. And when they work they don't do so well. Save yourself the trouble and buy an external modem ( serial not USB ), but come to think of it the price tag on those makes it more economic to get DSL.

3D accelerated cards are confined to Nvidia based cards and ATI cards. Nvidia's drivers are in my experience much better than ATI's drivers. So if you intend on playing the few mega-games that do work under linux ( using emulation ) Nvidia would be a sane choice.

Sound cards all work better than in windows ( yes believe it or not ).

Scanners provide less challenge, check on http://sane-project.org/sane-mfgs.html to be sure.

As for distros, current viable options are Knoppix and Phaeronix , Hey why not ;) LiveCDs for testing, Mandrake and ubuntu for installed distros.

Hope I have helped :)