is it possible to run a full version of windows 98 on a nvidia 650i

more than likely yes but the mobo brivers wil be generic and you can,t use all the capabilities of the mobo

I wouldn't recommend it, odds are nothing will work that is integrated and it may even be unstable. Windows 98 is now 10 years old and that motherboard just came out, everything today is made for the nt based os, xp, vista etc.

You can try it, see what will happen but it won't be pretty.

If you are simply going to install it so you can do an upgrade to xp or something, that will work fine however its not going to function very well and a whole lot of drivers are going to be missing.

Should likely use a FAT32 format. If you need it for a particular program, suggest you dual boot with 2000, XP, or Vista