To clear the junk from my PC, I would do it in steps:

1.) Remove all internet rubbish - enter "Internet Options" from the "Tools" menu in Internet Explorer. Clear History and Delete Cookies. Click "Delete Files" under "Temporary Internet Files" and tick the checkbox "Delete all offline content".

2.) Clean-up registry, use one of several registry cleaners available on the 'net.

3.) Run "Disk Cleanup" as well as Defragment the HDD.

4.) Remove all spyware, ads and pop-ups; use Ad-aware or SpyBot Search & Destroy for this, and to top it off, do a virus-scan.

5.) Delete any files that you do not need and burn to DVD+/-RW or CD-RW.

6.) Go to Add/Remove Programs and delete programs/games that are wasting space.

Good luck!