Quad-core vs. dual-core

Will the following differ much with nginx for an upstream webserver
(running PHP and fastcgi) and accessing files over NFS?

Quad-core Xeon 3220, 2.4ghz, 2x4MB
vs.
Dual-core Xeon 3060, 2.4ghz, 1x4MB

Both with 4GB RAM, gigabit ethernet, SATA2 7200RPM disk.

It should work very well either way, right? I don’t think I’m using
the quad cores that much…