Buying new motherboard. AMD or Intel?

AMD or Intel?  I hear Athlon is way better than Pentium 4.  Also, what's the 64-bit thing for?  Overall improvment to your PC?  Good for gaming PCs?

Intel is better supported, and if you want to use your rig for games you're going to want an intel because it's got the genuine advantage of having an authentic pentium instruction set whereas what AMD puts out is mostly cobbled together crap they've pieced together out of specs they've pulled out of the dumpsters in the intel parking lot. To answer your question, 64 is five less than sixy-nine, if you catch my drift.