If you can install x64 then I'd imagine it's a problem with your WXP disc, although that would give a 'could not find file......' message probably.
If you do find it's a problem with the disc, either ring up and get another or you could probably just get one off the Torrent or something like that and use your existing CD Key and activate that - it's basically just like borrowing a friend's disc.
I'm now wondering if it's an overheating problem with the processor. I'm trying to play oblivion and after i start playing for a bit the whole computer just shuts off like it did while i was installing xp pro. Tried playing world of warcraft also and it shut down a few minutes into the game. Checked pc temp right after and it was 82c
that is way high for the 64's. Re-seat the heatsink on the proc and make sure that there is thermal tape/grease and that there is no plastic or anything but the grease between the sink and the proc. Also make sure the sink is seated well in the plastic base around the proc. (when you pull it off look at the imprint in the grease on the sink and see that the proc is actually contacting it)
Also, ultraviolet is right: what power supply is it (make/model) as many models conflict w/ the Asus board. (especially some older antec models)
Update: I took off the hs and the paste that came on the hs was really thinned out, so i went out and bought some thermal paste and now the load temp only gets up to 64c which is alot better the 81c and shutting down, so thanks to all those that replied.
I have the same mobo and that issue with WinXP installation... it was memory timings.
I had it set at 1T command rate, and with 4 mem modules it can't be done. So, during the install either it shut down, or rebooted. With 2T command rate it ran just fine.
It seems this is not your problem, but it could have been 8)