Improving System Performance

If I've got this in the wrong forum, by all means, feel free to move it. I'm fairly certain this is the correct one, however.

Anyways, around May/June last year I finally put down the money and bought a Laptop. I decided, since I'm never in the same place each week, between my apartment, back home, and the labs, that I'd prefer to pick up a Laptop to replace my desktop. I ended up going with a Dell XPS, and I haven't had any real issues with it, so I'm pretty happy all in all.

However, a couple of months ago, despite scanning everything I ran, I managed to get some spyware I couldn't get rid of. I ended up choosing to reformat, ( with Windows XP Media Center Edition) to solve my problem.

In order to get the proper drivers I put that Dell shit back on, and hand picked the garbage out of that mess. However, since reformating, I've had a few issues with my system.

Now, it seems to me that the fans seems to kick on "harder" and sooner, under less "pressure" than before. In Oblivion, for example. Before the reformat, it ran pretty strong under "Super High Settings" or whatever that category was, and the fan would only kick on after a bit, and only for a little while. Now, however, it kicks on pretty damn fast and stays on.

Some other games give me a slight, high-pitched noise while running, though, that may be an issue my sound card, as when I plug headphones in it goes away. (Altogether, not just that I can't hear it with the headphones on).

I figure, perhaps, that it may just be a driver issue, but I did pick up all of the latest drivers when I reinstalled. It also seems like a lot of my memory is being used, with 1GB of RAM, but roughly under half "available."

I should also mention that I do defragment frequently, with Diskeeper.

I suppose my question is does any one have any recommendations for improving system performance, be it through other software, or just regular advice. Any assistance would be appreciated. Thanks!

Jam it back in, in the dark.