Id just like to point something out:
"% overclock" is meaningless.
get an X2 6000 to 3.1 ghz, and its a seriously low %, get an X2 3600 to 3100 the % is much higher, but chances are you have the exact same actual silicon in there (well, 50% cache disabled, but thats not my point) getting the X2 chip itself to 3.1+ its what counts.
what counts *really* is the end speed.
the C2D core is the C2D core. if you get a C2d that gets 4 ghz on air, thats a very well made C2D. but its still a C2D, same as the C2D that only makes 2.7ghz.
with the above: the 2.7ghz C2D might have started at 333mhz, a truely awesom % overclock then, but truely dreadfull for C2D chips.
% oc = E-peen (and money saving)
Max oc = Real World Use
now, amd have messed up sockets a bit this time round, with the old 700 socket, 939 am2, and am3. but they stuck with socketA for about, a gajillion years.
intel are guilty of this also, old P4's had 1 socket, then new p4's another, and now theres yet another
you buy what you want to get, you spend how much you want to spend, you get the best you can. your a fan boy, your not.
me - i avoid NF boards and cards, i just dont like n-vidias for some reason, i admit that. so i have ati cards on VIA mobos. i enjoy the feeling of getting "rubish oc boards" to oc nicely
To the OP - good luck with new machine, sounds liek a good one. i hope it serves you well,a nd i hope the server does also!