The Opterons are not Venus, they are San Diego too. Only s940 1xx Single Core Opterons code name is Venus.
Yes an Opteron is the CPU of choice if you want great performance, awesome overclockability (better than A64) and low price.
But for the price of the A64 4000+, I think you'd be better off adding some more $$$ and getting a Dual Core (DC) Opteron 165 (if you can find it) or a 170. These will own any single core system in everyday use, it will overclock like no other, it will be plenty fast for any current game. And another thing with a DC chip you're also future-proofing your system, there are already some multithreaded games and nvidia already has multithreaded drivers out for their cards, so a DC Opteron is a way better buy than a single core chip, if you can afford it.
The only reason for going single core right now would be if you can't afford a dual core (even by cutting corners).
Dual Core was the future a year ago, right now its becoming the present, don't get stuck in the past.
