There are lots of way to "wipe" your PC, but most are considered VERY unwise.
IF you post the specifications, manufacturer (i.e. Dell Tiny,HP, whatever), the Operating system in use,and a more detailed description of the problem, then i can give you more detailed help.
In the meantime however, you can speed up things a little by doing the following:
1 - Delete all your temporary files
2 - Delete all your cookies
The simplest way to do this is to open up a browser window. Then click on tools, then internet options. YOu will be presented with a series of buttons. CLick on the buttons for "delete cookies", and "delete files".
Also check to see what prgrams you have running all the time. Usually such things as your Firewall and Antivirus can slow down a machine. Also many other prgrams can slow down speeds, such as download Accellerator.
Run a search in google.com for spywareblaster. You should find several prgrams that can be used to sniff out and remove prgrams that tie up your bandwidth in the background.