Look up files with Bitzi before download: How to use Bitzi
If other users have rated the file, you'll see whether it's good or not.

There are lots of fake files around now, which won't play.

Check out these threads for more info about what to avoid, some general virus info & info about fake files:
Virus thread: Typical virus spam file sizes - Make a note of them (click on blue link to see)

* WARNING: Viruses on network you should be aware of ! *

Fake files showing up in search results

How to find music