Mac OS X 10.3, Panther, has built-in ZIP compression functionality in the Finder. Use it instead of stuffit. The ZIP format is more standard, and cuts down on problems with the Wintellians.
To create a ZIP file from anything, select the items in the finder, right-click, and choose 'Create Archive of [something]'. A file is created with the extension .zip. If you archived one item, the zip will have the same name. If you archived more than one, the file will be called 'Archive.zip'. Seriously consider changing this name to something more descriptive.
The original files remain.