absolutely go SATA, I would rather go with the x2 3800 then go ide. the speed performance on the disk is incredible on a 16mb cache drive. hell even on an 8. And to all the intel vs. AMD zelots out there, use what you like. I use both and personally I like the performance/price on amd.
Word of warning!!!!! before you rip open that windows xp64 make sure the drivers are solid for the board. Once the pack is ripped you can't return it. I just ran into that exact problem on a dual opteron 248 system. Asus didn't make 64bit drivers for anything. You may want to stick with xpsp2 since 64 still feels bare and the apps aren't there yet.