Lefteris already gave you a link to the software you need to unpack these files.
I just hope the files contained in these .SIT files are plain ROM files that are usuable
on any system, otherwise you're stuck -- there are Apple Macintosh emulators,
but the most recent Mac OS they run is about Mac OS 8.1 or so (and current version
is about 10.3.5 -- not to mention Mac OS 10 is a COMPLETELY different system).