Something to keep in mind on laptops..
Several things that can't be changed: Video cards and screen size.
Get the screen you want and the best video that you need. These are things that are not changable. The Processor in a lot of systems can be upgraded a little, so can memory. It's best to get the higher end chips though so that you don't have to worry about it in the future.
Something else to keep in mind is battery needs, if any, and function. Most of the highend notebooks will work just like a desktop for most stuff, but in some cases they run a lot slower. so doing cartoons and playing a few games won't be hit too hard, but if you plan on playing games all the time, you will see problems, especially with the newer games. The more memory you have on a laptop the better.
Don't install unneeded applications either, as they tend to take up additional resources.
I'm giong to assume that you are installing XP and will probably have an office variant. My suggestion is to use office 2000 not xp or 2003. It takes up too many resources on a laptop. It works fine on a desktop, but on a laptop, it takes way too much away from other functions. Also, stay away from Windows media on the machine. Use something else.
My 2 cents...