In addition to clearing your browser history you will need to empty the cache by selecting it from the Safari menu and removing the cookies from the Preferences Menu. You can hold down option, command, and E to empty the cache.
Do you have an iTunes Music Library, use Mail, or talk using an instant messenger? That can also take up more space on the hard drive.
1.66 ghz Intel Core Duo Mac Mini w/ Mac OS X 10.5.1,
400 mhz Power PC G3 iMac w/ Mac OS X 10.4.11,iPod Touch 16gb, Maxtor 80gb HD, Lacie 500gb and 250gb HD, 4th-generation 20gb iPod.