Quad Xeon or Quad Opteron?

Hello,

 We're planning new production server for PostgreSQL and I'm wondering
which processor (or even platform) will be better: Quad Xeon or Quad
Opteron (for example SUN now has a new offer Sun Fire X4440 x64).

When I was buying my last database server, then SUN v40z was a really
very good choice (Intel's base server was slower). This v40z still works
pretty good but I need one more.

AFAIK Intel made some changes in chipset but... is this better then AMD
HyperTransport and Direct Connect Architecture from database point of
view? How about L3 cache - is this important for performance?

Do You have any opinions? Suggestions?

Thanks,

Best regards

--
Andrzej Zawadzki