Emmy:

in FireFox go ‘Tools->Clear Private Data’ and tick the categories that you want to clear and obviously detick the categories you don’t want to clear…
I’m afraid i can’t use IE on my mac but i would expect it to be similar or more like Safari where it has ‘Empty Cache’ under the Safari drop down.. just search through the drop downs at the top of Explorer and look for ‘Empty Cache’, ‘Clear History’ and possibly ‘Clear logins’ or something to that effect. if you can’t find it in the drop downs look in Preferences.

As a mac user i can’t really help with the increase in speed but i did use a PC about 5 years ago:
1) clear the Desktop (as the computer continually loads it)
2) if your background changes stop this (as it times between changes, finds the correct picture in the directory etc)
3) clear some space on your computer (mac’s work at their best with 10GB free Disc space.. i’m not sure how much is best for PC’s but i do know the more space you use the slower the computer gets)
4) if you have a Dock(a copy of the Mac Dashboard) close the unessential Gadgets(copy of Widgets)(see 1 for the reason)
5) close anything that isn’t essential for the computer running… you might find them by looking in the.. i don’t think it has a name… the Ctrl+Alt+Delete window.. or down in the right hand corner of your screen shows some of the programs running in the background close them..

well there you go i hope this helped and just so you know clearing up disk space is a really great way to make your computer run faster you could also try getting a computer with more RAM or virtual memory or get a quad processor(process’s data 4 times as fast).. though it might be better to get a computer with the quad processor included just cause you might find that the processor on it’s own might cost more then the new computer though i haven’t checked this

Blue:

Download & run Ccleaner. It will keep your computer clean.