I think he bought a used PC with a 20GB HDD and 512MB RAM, and he partitioned the HDD. After (or during?) the OS installation (Windows I assume) he noticed that the system is running slow. He was advised by someone else that an OS already exists on the HDD/partition and that might be the cause of the poor performance. He wants to make the PC to run smoothly.
It's impossible to give a solution without more details about the setup, but a few thoughts:
(1) Hardware problem. A 20GB drive went out fashion ~ 5 years ago, and probably the one in the system has seen considerable action and is not in good shape. A HDD replacement may be necessary.
(2) Insufficient RAM. Up the RAM to 1GB atleast.
(3) Reformat the drive, remove all partitions (no point partitioning a 20GB drive) and reinstall Windows. Install/update all the drivers.
Can't think of anything else at this stage.
