I've been reading posts saying I'd get more bang-for-the-buck with an
AMD setup than a similarly priced Intel setup, so I'm looking into
it.

The CPU/board combinations I listed in the subject line seem to be
similarly priced as near as I can tell. However, when I compare them
at
http://www23.tomshardware.com/index....2=112&chart=21,
it looks like they perform pretty equally with games and the P4 630
finishes quite a bit higher than the A64 3000+ on video encoding.

Also, what's the difference between socket 754 and 939?

Again, I've always been an Intel guy but am looking for an excuse to
switch to AMD. Can someone please explain this to me?

Thanks!

Tim