Spring cleaning your gadgets isn't confined to just their surfaces — your desktop and hard drive need to be spruced up as well (the better to keep you running, my dear).
And what does everyone do? We throw files into the trash, and then conscientiously empty the trash.
Even after you've emptied the virtual can, though, your deleted files still exist.
Want to get rid of them for good? Then use this feature (for Mac OS X Leopard only): Secure Empty Trash.
Just select Secure Empty Trash from the Finder menu, and when the pop-up asks you to confirm that you want the items in the trash permanently erased, click OK. Poof, they're gone.