I am looking at basic laptops and am wondering what the difference between dual core and core 2 duo is. The comparison charts I found don't show much difference. The core 2 duo is the newer one right ?

Oh and how does the Athlon 64 X2 compare. Last time I looked into this stuff intel was the way to go for mobile.

Dual core is just a generic term to mean two processors on a chip.

Core 2 Duo means it is the second generation Core chip from Intel, with Duo meaning it is a dual core one. There are Core Duo chips, being the older first gen ones, and also Core 2 Solo and Core Solo chips that are just a single core processor.

Athlon X2 chips are also dual core.

And while I haven't been keeping exact tabs on the mobile market lately, I do remember it being said Intel is generally on top still for higher processing power and lower power usage.

I remember there being core duo but now I am seeing dual core instead maybe those are the older core duo ones.

It isn't quite that simple unfortunately. Intel for some reason have decided to make their product range complicated.

Celeron - Could be anything from a Pentium 2 based chip up to the latest Core 2 series. Always single core however.
Pentium D - Two Pentium 4 based cores. Not made any more.
Core - Original Core architecture - Comes in Solo and Duo variants
Core 2 - 2nd generation Core architecture - Comes in Solo, Duo, Quad (Only desktop at the moment) and Extreme variants
Pentium Dual Core - Low end Core 2 CPUs

If it doesn't specifically say "Core 2 Duo" then assume that its either a lower/older model or that it isn't Intel. The latest and greatest currently is Core 2 Duo/Extreme.

So which one would you guess Pentium(R) Dual-Core Mobile Processor T2370 (1.73 GHz, 1MB L2 Cache, 533MHz FSB)is ?

It probably isn't even worth worrying about for a laptop that would pretty much be used at home for internet browsing but I like to try and find the best deal.

"Pentium Dual Core" is the new name Intel is using for what was known as the Celeron line, aka the low end. Celeron was discontinued in January. What Trevor said applies to what you are looking at:

Aren't the solo's simply a dulie where one of the cores failed and was programmed off?

If there's enough supply of half-duff dual core chips, then they could conceivably use them alone, but more than likely the have to supplant them with real single core chips.

Intel and and others, like ATI, have done this for years when chips wouldn't run reliably at their intended clock targets. ATI sometimes introduced a whole product just to clear out these binned parts. Sometimes also disabling a pipeline here and there or sometimes it was part of the failure. AMD does it now with their 3-core processors that are actually binned 4-core parts as far as I know (and have been lead to believe by my informants ).

supplement?

Initially yes but they probably are real single core chips now. When the chips are first made then the yields will be low and they will get lots of partially dud dual core chips. Once the yields improve then they'll want to make real single core chips which are cheaper because they're smaller etc...