Can i make a suggestion that worked for me. if you go to my computer and right click your drive.
click clean up. Make sure after its done its thing and presents you with some options. That You tick the box hibernation files old versions of Vista if you done any reinstalling. make sure there all ticked.
You should see a big lump of stuff go.
also the CC cleaner a good tip as suggested.
But as well as that i also have Privacy eraser for 30 days now why i have this is To get rid of my cache you can try it by all means.
its worked for little me i was in the same ship :))
http://www.privacyeraser.com/
One more tip: Download and try Google chrome its so fast it has its minus but when you learn how to drive it its ok remember click the spanner in the top right hand corner and chose clear browsing data.
i have also installed
antivirus http://www.pctools.com/free-antivirus/ checks all the email in and out but most of why i have it when you get a mail from me it has no virus found written on it checked by pc tools. which i think is nice.. reassuring for others.. looks like you care too
firewall http://www.pctools.com/firewall/
spyware terminator free http://www.spywareterminator.com/ it has a resident shield built in its brilliant
i don't get any of the spyware and malware problems these guys get because i don't go to porn sites to be honest
well not yet anyway.. :))