nukes
I can try and answer some of your questions.
Generally speaking most nforce2 mb's do not work well with generic or oem ram, but who knows you may be the exception.
Is the video card 3.volts or 1.5v as required by most nforce2 chipset boards?
Based on the hardware you have, when you add a nforce2 board into the equasion, you can expect to have power problems if the 12v, 5v, and 3v outputs are not adequete, nforce2 boards draw more power than via boards, and alot of users that have migrated from older via-sis, whatever systems have discoverd that their previous power solution is no longer adequate.
As far as multiple ide channels, the gigabyte series of nforce2 boards feature 4 ide channels in addition to the two sata channels, thats the reason I have gigabyte, the extra ide capabilities.
Dont know about linux compatibility.
Good luck with your search, but above all else be prepared, with most any nforce2 board, ram and power supply are major items.
Laterz,
dafanman