I don't know too much about BIOS and stuff either but if you can't upgrade your BIOS to support more than 60gigs, get a 40gig harddisk or something.

If you got the cash get a new processor and motherboard

Or actually just get a new computer! you can get a pretty fast pentium 4 computer for less than US$600 including a 80~120gig hard disk!, 256~512RAM, but excluding the monitor of course

And also about Buffer Speed - the MORE the better/faster. But 2mb is fine.