nginx performance/preference - FreeBSD 7 or Linux 2.6.x (both 64-bit?)

[mike]

Currently I have nginx running PHP/fastcgi and normal static content
on a quad-core xeon 3220 w/ 4 gig ram.

I am looking at moving this to a dual-core xeon 3060 with 2 gig ram.

Would FreeBSD 7 (or 6, I suppose) be better than Linux for this? Each
server (there are 3) gets approx 33% of a few million HTTP requests
per day (1-2 million are PHP/fastcgi)

Thanks :)