John Stumbles gurgled happily, sounding much
like they were saying:

One thing I'm wondering is if it's worth going for a machine with a lot
of RAM - which AIUI requires a 64 bit CPU to access if it's over
2^mumble bytes

4Gb, and it's 64bit OS rather than CPU.

but I don't do gaming, so I guess I don't need fancy 3-D acceleration
or whatever.

Probably not, but double-check that Compiz supports the graphics. I love
Compiz.