If using explorer, go to tool > internet options > general tab > look for a section on 'History' click on the 'Clear History' button and watch them dissapear.
If Netscape go to edit > preferences look for 'History' and do a 'Clear History'
Go into START, select settings, then Internet options. Find 'History' settings and delete history. To avoid this happening again set the time limit for 'History' to 0. This way at the end of each session your history will be wiped. Also it is a good idea to empty your temporary files too and keep a check on the cookies being placed on your system. I suggest also getting a third party program which will enable you to surf without trace (try www.download.com)
While deleting your history seems to wipe your tracks it doesn't.
Go to Find. Click find Files.Click to C drive.Type Temp. Click find now.when all files are
found click edit then select all,click file select delete.
you will be prompted as to weather to delete if a file used by programs.In windows the essentials are write protected.
Repeat for cookies. You probably have 10,000 or more cookies if you have been on line for six months and it is eating up hard drive space.Each cookie tells about a page you have visited.Each page loads from four to 28 cookies each one with the url imbedded.