nforce2 is only athlon xp.
k8t800 is pretty good. I have one wiht my athlon 64 and its pretty good, it is much faster than my old 2.1 athlon xp.
Although socket 754 is good(what I have) socket 939 boards are the future. So if you ever want to be able to upgrade the proc even somewhat significatly then you might want to consider a socket 939 cpu and mb.
also pci express boards are just coming out for amd, if you are looking at a videocard upgrade as well consider a board with this slot. The only ones I currently know of are a gigabyte, a chaintech, and that asus board(this is made for dual videocards and is way out of your price range)
I usually buy form
www.newegg.com as they seem to be almost the lowest price(they also have refurbished motherboards for alot less) and better service than most.
Also the pricewatch thing is a good idea to avoid getting ripped off. Also remeber you probaly need new memory.
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