i found thousands of gifs on my hard drive, almost by accident. from what i can see, they are things like cfc smilies, avatars, and the yahoo 'new mail' button. is it safe to delete them all, or might some windows stuff be hidden there?

I expect they are your temporary internet files.

These are saved onto your hard drive whilst you're surfing, so that when you re-visit a page images that you've seen before can be loaded from the HD instead of being downloaded, thus speeding up your surfing.

If it is this, you can safely delete all the files in the directory. You will find that there will also be some web pages, applets and the like. This can all be deleted, too, just bear in mind that if you don't change the internet settings, the directory will start to fill up again. If you're not pressed for disk space, I wouldn't bother clearing the directory.

The settings can be changed under 'Tools>Internet Options' (for Internet Explorer).

I make it so that everytime I close IE my temporary internet files automatically are removed. And at the end of each day I run Window Washer to clean out my files and wipe my index.dat file clean.

is window washer a free program because my disk cleanup doesnt work if i try to use it, it just crashes my computer. :(
does anyone know of a free program which does the same job
thank you in advance

Window Washer is not a free program - they give you a 30 day trial.