You may want to check out the <A HREF="http://www.abit-usa.com/eng/product/mb/kr7a-raid.htm" target="_new">KR7A-RAID</A>. It's a KT266A board, so you'd have to replace your memory, but hey, memory is dirt cheap right now. It's a pretty sweet looking mobo though. Athlon, 4Dimms, 6PCI, KT266A, Abit's softmenu for overclocking... the list goes on. I haven't heard anything about stability or reviews yet though. I think this one comes out the end of Nov, which isn't too bad a wait really. It looks pretty promising.
I've been using the shuttle ak31, version 3.1 for about 3-4 weeks, and had no major problems with it ($85 newegg). The only thing I had to do is enable the cmos jumper before the board would boot up with a 1700 xp. You might have to flash the bios if you get a board with the older bios version. The bios version that recognizes the xp has a 9 instead of 8. The new xp's are locked, and you have to use a rear window defroster kit to unlock them. If that doesn't appeal to you, I would suggest a 1.33 regular athlon instead. I noticed very little difference in speed with my new 1700 versus my old 1.2 overclocked.
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As I know in order to use your old rams you must have a pentium based cpu again. If not, I can suggest to have a DDR ram combination with a KT266A Athlon boards such as MSI Pro2-RU.
If you want to go on Pentium 4, please wait a while to get new SIS chipset based P4 boards that supports DDR ram technology.