Overdosing on "exe" files, HELP!!!!!

I am new to everyting and I don't know sh*t.
I am on Power Mac G4.
I only download "sit" & Z"zip" files.
But 90% of those I unstuff turn out to be "exe" files which I assume are for PC, which is why I can't use them.
Is there any way I can ID these worthless downloads and save the waste of time?

Here's some thoughts:

My first suggestion, post your thread under General Mac Support to quickly reach people with Mac OS specific expertise...

Second, I would do a search of this forum for .sit
For starters you can check here and here also.

Hope this helps.