Deleting files for good!

If I downloaded something that turned out to be a file that I didn't want or was falsly labled, and I delete it from both the shared folder on my computer (runing OS 10.3.2) and my library in Limewire, is the file really gone? How can I get rid of something completely and hopefully have no trace of it or be associated with ever having it? I'm sure this has happend to some people before: A file says it is one thing, but you download it, open it up, and it's something you probably shouldn't have or want.

Thanks in advance for any help or advice

Find the file on your hard drive, trash it and use the Finder->Secure Empty Trash

Look also in any program that opened the file to clear any "recent" list, such as the Apple Menu->Recent Items.

I guess if someone really wanted to see what had been on your hard drive there are still ways (very expensive; try Google), but very unlikely.