I am thinking of buying a Laptop for my transport needs. I have a pretty good Desktop that handles all of my multimedia and gaming needs and I REALLY want to avoid paying anything more than what I have to thus, setting myself a pretty tight budget.
Plenty of models to chose from but not quite sure of how to evaluate their CPU and GPU specs as I cannot find any kind of a comparison between them.

So, all the models that I've found had the following CPUs and GPUs, all of them from somewhat old to flat-out obsolete but, as long as they're enough for my needs they'll do. When comparing them more than to know which is faster I also need to know which is the most power and heat efficient. Also, I not only want to know WHICH is better but also BY HOW MUCH:

CPUs:

• Core Duo T2130 (1.86 GHz)
• Core Duo T2310 (1.46 GHz)
• Core Duo T2330 (1.60 GHz)
• Core Duo T2370 (1.67 GHz)
• Core Duo T2370 (1.73 GHz)
• Core Duo T5250 (1.50 GHz)
• Core Duo T5450 (1.66 GHz)
• Core Duo T2450 (2.00 GHz)

GPUs:

• Intel GMA x3100 up to 348 MB / 251 MB
• ATI Radeon Xpress 200M 128 VRAM (it is unclear to me how much, if any is dedicated and how much is shared memory, however, this one is in my no.1 choice so...)
• ATI Mobility Radeon HD 2300 128 MB integrated, up to 896 MB shared
• GeForce 8400M G 128 MB integrated, up to 895 MB shared
• GeForce 8400M GS 256 MB integrated, up to 1024 MB shared
• GeForce 8600M GS 256 MB integrated

It's obvious to me that the integrated solutions aren't on par with a 8600 but all I want is to be able to watch in full screen (1280x800) the occasional matroska video with H.264 1280x720@30fps Video, AAC Audio and A-SS Subtitles and have some basic 3D acceleration support, mainly for applications like Compiz and an old non-demanding DX 8-9 game for when I'm traveling or sth...

Ok, maybe I didn't make myself clear enough, what I'm asking is some type of comparison telling me their difference in processing power, power consumption and heat production.

FWIW I already was able to make heads from tails about the GPUs and I already know the gist of which cpu is the "best" in terms of performance.
However what I want to know is HOW MUCH BETTER, and at the cost of how much more power consumption (if any) and heat production.

If you can help me first hand or know of a source about those please do tell me...

Note that some of the CPUs you mentioned, such as the T5250 and the T5450 are Core 2 Duo processors, which are quite a bit better than the Core Duo processors (because of a better architecture).

As for a GPU, as you say you want to play some older games, I'd suggest the 8400m GS. You don't really need the 8600m GS if you're playing really old games.

I'm not going to suggest anything until I know what your price range is, so...what is it?

That's just it, CPU models are a complete mystery to me!
I'd definitely prefer the CPU that is most probable to handle not only today's but also tomorrows applications (especially true if some CPUs are 32 and others 64 bits).

My price range is low, 600 to 700 euros and all of these I found on PCs within that price range (although to cut cost when they put too much of one the took out in the other...).

Yeah, I pretty much figured out that 8400 GS was the top choice for my needs. I just didn't know how far behind the x3100 or 200M was for instance.
I'll probably be playing games to the extent of Warcraft III or Hitman. No FPSs here...

I had a 2300HD, it got taken , and I replaced with a much cheaper intel 3100. the 2300 was at least twice the GPU. if money want so tight, I'd have got at least a 2300.
I bet some new laptops will be out soon with AMD's 780g north bridge, ATI 3200. that should be a good setup

I don't know if that will ever be within my budget but I'd wait anyway, it seems what I'm truly after (a cost-effective <15" laptop) is slowly on its' way...

gateway sells refurbs on ebay. some are quite cheap, other not.

the 780g, when it comes out, should be fairly cheap, as it is integrated graphics, just better done than any previos version, and AMDs are cheaper in general

I live in Greece, I doubt they ship here (and even if they do I doubt they'd cover me with a warranty...)

Where can I read up on the upcoming models?

As I said I'm not particularly in a hurry to get it as the more I look into it the more I feel this is a bad time for what I want...

Notebookreview.com is a pretty good site for reviews and such. Worth a look.