You should rather go for a Core 2 Duo, instead of a Core Duo or Pentium M. You will find that the Core 2 Duo is Streets ahead of the others.
Notebook processors fall into three main categories:
1) Budget processors: These are the Celerons and Pentium Dual-Cores of the world. They are often stripped-down versions of more expensive processors. These processors are usually too slow for and real gaming, but they will be able to run most office applications. Not recommended for multi-tasking.
2) Mainstream processors: These are the Core 2 Duos and high-end AMD processors of the world. These processors are adequate for pretty much any game, since your bottleneck will most likely be the graphics in your notebook. These processors will be able to handle any office application you throw at them, and then some. Recommended for multi-tasking.
3) Enthusiast processors: These are the high-end Core 2 Duos. The AMDs don't really feature in this segment at the moment. Enthusiasts are looking for performance, and unfortunately, buck-for-buck, the Intel processors in this segment edge ahead each time. These processors will not give you trouble with current games (although your graphics still might), and will be able to handle any application you throw at them. Be prepared to pay for this convenience, though.
I would suggest an Intel processor.
Intel platforms fall into a few categories, since Intel brands their mobile platforms as some flavour of "Centrino", which encompasses a compatible processor, chipset and wireless adapter. In increasing performance (and from oldest to newest):
1) Carmel platform: You're not likely to find anything in this range these days
2) Sonoma platform: You're not likely to find this either.
3) Napa platform: You might find this on some budget notebooks these days. Having owned a notebook from this era, I can say that the performance for office productivity is more than enough, and coupled with decent graphics, you'll be able to play decent games at decent frame rates.
4) Santa Rosa platform: You'll find a lot of these around. However, you might not find Centrino-branded Santa Rosa notebooks. This is because many manufacturers have opted for non-compatible wireless adapters. Even better than Napa.
5) Montevina platform: The current state-of-the-art. The Centrino-branded versions of these notebooks (actually, "Centrino 2" branded) are currently very expensive (twice your budget). However, you can find notebooks with Montevina chipsets using Santa Rosa processors that are EXTREMELY well priced.
With regards to graphics, you have 3 main choices:
1) Integrated graphics: Intel's integrated graphics are better than they've ever been. They now include some hardware-implemented acceleration, which improves performance dramatically. You will be able to play almost any game with them, but only at very low frame rates. Sadly, even with the performance increase over previous integrated solutions, even the most entry-level discrete graphics tends to out-perform these.
2) nVidia graphics: nVidia graphics are some of the best you can get. Currently, you can find notebooks with 9300M GPUs, which apparently perform exceedingly well. In reality, expect this GPU to perform about the same as a mid-range desktop GPU. Often more expensive.
3) ATi graphics: Many manufacturers are shipping notebooks with ATi graphics. The reasons is their performance-per-buck.
With regards to memory, you should look at what operating system you are getting with the notebook and what operating system you wish to run. It's pointless going for 4GB RAM if you aren't going to be using a 64bit operating system.
I recently bought a notebook with the following specs, and have been very happy with it:
Intel GM45 "Cantiga" chipset (This is a Montevina chipset)
Intel Core 2 Duo T5800 @ 2.0GHz (This is a Merom-based Santa Rosa processor)
2 x 1024MB DDR2-800 RAM
Intel Integrated 4500MHD graphics
At the end of the day, unfortunately, R6000-00 is currently not going to get you very much in the way of branded notebooks. You could look at the Sahara or Mecer notebooks if you don't mind the brand. Many forumites are big fans of Sahara because of their performance-per-buck.
