For a fast PC it is best to not use such things as Google toolbar or Ask toolbar.
It is also a good idea to clear your history and cookies at least once a month. For those who use more than one browser(ME) it can be time consuming though, that is why I use Ccleaner by Piriform. It clears all your history and cookies and it also has a handy registry scanner and cleaner. But you must remember that you will need to remember any login info for any websites that you may use as it will delete then.

It can be downloaded here http://www.piriform.com/ccleaner/download/standard