Yes, Packard Bells have hideous HD installs from the factory. Go to 'Control Panel' (under settings on the start menu), and 'Add/Remove Programs' - you can remove programs using an automated system from there, provide you havn't accidentally deleted the script that usually sits in with the program itself. Most Windoes programs put files in system folders, and make changes to the Registry (a database of everything in windows), so if you remove a folder you're only getting part of the space used back.
Also remember to empty the recycle bin (right-click on it) as that counts as used space when checking disks. You should be able to free some space by getting rid of programs, but the only way to make Windows 'lean & mean' (comparatively) is to format the harddisk and re-install carefully - Win95 with sound, video and Internet can be cut back to about 50Mb. Don't try that without being sure what you're doing though, as getting Windows to run well is an art form (getting it to run shabbily is easy, lol).