>I have obtained some price quotes for a new computer, and the big rage seems to be the Intel Core 2 Duo. Specifically, I have two offers from the same company, one without this Core 2 Duo ("Pentium 4, 3.2 GHz"), and one with ("Intel Core 2 Duo, 1.8 GHz"), with similar prices. Actually, the slower (in clock speed) Core 2 Duo is slightly more expensive.
>
>Would the much slower clock speed be sufficiently compensated by the fact that - as I understand it - there seem to be two processors on one package? Is it really two processors? How well do the two processors work together? In summary, from which of the two - faster, single core, or slower, double-core - can I expect to get a better performance?
>
>Of course, I could also go for a higher clock speed, but it seems those are quite a bit of price difference for those, so I was thinking of the slower (and cheaper) models.

The Pentium 4 is single-core and uses the relatively inefficient (both in terms of power consumption, and work done per clock cycle per core) NetBurst architecture. Note that there are dual-core NetBurst CPUs but these are marketed as Pentium Ds.

The Core 2 Duo architecture is a major advance by Intel, with both low power consumption and greatly improved processing performance per clock cycle ( http://en.wikipedia.org/wiki/Intel_Core_2 ). Even at relatively low frequency they perform well against NetBurst CPUs. Tom's Hardware CPU charts gives you all the comparisons you need: http://www23.tomshardware.com/cpu.html

You can compare the Core 2 Duo Allendale 1.8GHz against the Netburst Prescott 3.2GHz for any benchmark you'd like. You'll likely see big differences in benchmarks that can take advantage of two cores, perhaps not so much when a benchmark can only use 1 core.