Notebook Gaming

I have some questions, I am in the market for a notebook system. I no longer wish to be required to use my desktop for all of my computing needs. I am just finishing my first year towards my 4 year programming degree and I enjoy gaming in my spare time.
heres the questions:
trying to be as cheap as possible due to being on a college loan budget, what should I be looking for in a notebook that I want to replace/perform equally to my current desktop configured with:
p4 2ghz, 512 ddr, geforce4 mmx440 64meg, etc.

mainly in a gaming sense, how do all of these mobile video processors on the market compare to the configuration i listed? How well do modern laptops run todays games? such as age of mythology, or any of the new fully 3d games on the market? What is the quality of gameplay? any slowdown? what about shared vs deticated? basically are laptops today capable of doing what I expect out of my desktop? or should I even bother? please reply only if you have experience in running modern games on notebooks.

what would be your recommendations for notebooks with similar performance if notebooks are capable of gaming like i would want?