I would recommend a format and reinstall an operating system and drivers
If you do not have drivers you should either try to locate them either on media or on the internet.
Another option would be to go to add/remove programs and take out everything but the basics, then go through your program files and look for anything thats left that you want to uninstall. There should be an uninstall icon if it was not on the add/remove programs list.
To take out webpages simply delete the contents of the temporary internet folders, and clear the cache. If you are using internet explorer, just right click on the icon, go to properties, and click delete files, ensuring the "delete all offline content" box is checked, and click ok. This will clear Internet Explorer. You can also clear the history from that screen.
Now, if you simply want a clean hard drive, I would recommend just wiping it clean with a format utility like fdisk.
To do this:
*NOTE* if you have any extras in your computer such as modems, video cards, cdrw, Network cards, or anything else not on the motherboard itself, you should download the drivers and save them somewhere before you format, if you have the disks on hand dont worry about it.
1) obtain a floppy disk, ensure it is empty (format it if you have to)
2) go to
3) download free fdisk 0.99b
4) unzip the file to your floppy drive, also add format.exe from your c drive (start-find, files and folders, look for format, then copy it to your floppy disk.
5) insert the floppy and reboot your computer (shutdown and restart)
6) the computer should reboot to the floppy disk, where it will give you the command prompt A:7) now the fun part, you get to destroy something!

8) type fdisk.exe <enter>
9) choose option 3. delete partition or logical DOS drive.
10) select the drive(s) you want deleted
11) if you had your drive partitioned make sure to delete all partitions now.
12) This will leave you with a lump of free space. Now select the first option and create a new primary partition.
go ahead and apply all of the free space to that drive unless you really want to make partitions.
13) now select the 2nd option to set the partition as active (so it will boot up to it)
14) now if you are installing windows, go ahead, it will format the partition you install windows to anyways. but if you arent installing windows, you should get back to the command prompt (A:\) and type format c:
15) now your hard drive is clean. just install windows or leave it as is.
-Nick