Perplexing Graphics Issues

I have a Dell Inspirion 600m laptop. It has a Penitum M 1.5ghz, 512 MB ram, and a 64mb dedicated radeon mobility 9000 graphics card.

Here's whats happening:

I log into Guild Wars, and I can play smoothly on mid-to-high graphics for about half an hour. Then, the game starts running choppy. Unplayably choppy. No amount of idling will change this. Indeed, I can shut down guild wars entirely, and even normal everyday operations like browsing the web will be significantly slower, until I reset.

What gives?

I would think that if the laptop isn't strong enough to run the game, it would be choppy from the start, not a half an hour after. Why does it play perfectly for only 30 minutes?

And if the game is what's so taxing on the system, why does the laptop run like crap even after I turn it off? I stopped playing over 2 hours ago and web pages still take longer to load; I mean, the *advertisements* even play in slow motion.
Ideas? Suggestions? Most appreciated.

You can always run your system through www.pcpitstop.com This will scan your computer and make suggestions as to what to "tweak" like your IE cache files and such.

I would think that having 1Gb of ram would take some of the chop out of it too...

Get a bigger ram size so it can run faster and smoother

XP really does need at least 1+ gig of RAM to run smoothly. Otherwise, you run into many virtual memory disk swaps, and everything grinds to a crawl in the meantime...

Run Spyware and Virus scans too.

They may not be a serious object that damages/keylogs your system but they may be some annoying object that slows down your PC a lot, believe me, Spyware slows your PC like mad.