Single Proc Multi Core Vs Multi Proc Single Core

This is kind of a followup of our thread
"More RAM or better CPU?" [url].

Sorry if we were supposed to post in that thread in stead, but this is a different question that in that post.

Our server is still crashing a lot and unfortunately we can't afford a multi processor with multi cores.

So the question is as follows:
For a site with a lot of database activity, what would be the best thing to go for:

a) Single processor with multiple cores, or
b) Multiple processors with a single core.

a = Intel Xeon 3060 Dual Core Conroe Processor (2.4GHz)
b = 2x Intel Dual Xeon 2.8GHz Processors