After doing a bit more research what I said above may not be totally correct.
I got a bit confused because Intel have a bewildering range of CPUs, all with similar names, and it is very easy to mix them up.
I stand by my comment that the Intel Core 2 Duo is the best.
BUT they do have some mobile Pentium Dual Core that are the same as the Intel Core 2 Duo but with less cache.
These numbers are T2330, T2310, T2130, T2080, T2060, T2370.
But they also have some Celeron dual core procesors, which are their budget range. the only number I could find is the T1400.
So if looking for a laptop there are 3 main choices with Dual Core:
1) Intel Core 2 Duo - the best if you can afford it
2) Pentium Dual Core - next best and cheaper
3) Celeron Dual Core - cheapest but lowest power
(Note they also have mobile CPUs called "Intel Core Duo", and "Intel Core 2 Solo" and "Intel Core Solo" so you see why I got confused).
You can read about their mobile processors here
http://www.intel.com/products/laptop/processor s/index.htm?iid=notebook_body+proc