My Windows Xp Disk Cleanup is Taking Hours! And I have still not reached the screen to direct it what to clean up. It's been scanning. Is There a Better Way to Clean up the HD? If software is an idea; I'm on a budget. Preferably I'm looking for good ad-free freeware or very inexpensive software.

I use an Compaq Presario SR1103WM when I'm at my Dad's house. We've had it for about 2 or 3 years, and used it for everything from games to internet to whatever you can think of. However, it's outdated now, but I can't afford any major upgrades or to buy a new computer right now, so I'm trying to figure out how to run it better. The only specs I know are:

248 RAM (8mb is diverted to video memory) max is 1 GB
Intel Celeron(P) 325 2.56 GHz
40 GB HD

I have no clue about what the video card is, I've had it 3 years and still can't figure it out. Sorry the specs aren't very informative, but you could probably Google the rest if you need it. Right now it's on a dial-up connection, which I only use for instant messaging. Like I said, as of right now I can't really afford to upgrade it, but here in about a month I can. We're also getting Road Runner for it, which should speed up the internet connection a bit. Besides upgrading it, what else could I do to make it faster?
Also, I have deleted a lot of old software that I don't ever use anymore, and I just figured out how to clean the hard drive, so I did that for the first time in 3 years and it is sped up slightly.