'sup, good Jes
The only silly questions are the ones left unasked.
Technically, what you plan on doing is wrong.
Having said
that, the odds of getting into trouble over it are extremely low. Typically, if you're just doing this to learn how to edit and only a few close people are going to see it, there's just no way the appropriate licensing authorities are ever going to catch wind of it.
It could be a problem, though, if you suddenly had a gem of a film on your hands and you (or a friend) uploads it to Usenet, where it becomes a 'net hit movie being downloaded tens of thousands of times.
I think most people have practised editing on whatever material they have on hand, at the time. Sound, video, whatever. Fake Budweiser commercials to build reels, etc. I've made a dozen or so short music videos using video footage from my favourite films and music from some fave bands. It's not stuff that I can flaunt about, but I sure learned a heck of a lot about editing doing it.
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There is a better solution, though.
There are a lot of composers out there, looking to try their hand at scoring a film/short. Doing it for free, too, just to be able to have something to add to their reel. Maybe try finding one? It's good for you, it's good for them... and if the short film you make turns out to be a real winner, you'll be able to actually submit it to an event or two without fear of copyright infringement.
There are more composers in the Classifieds section of this board, than you can shake a stick at.
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Dang! That was a long reply.
Short version. In the context you described...
Yes, illegal... but noone will care unless you launch it all over the 'net.
