The stars represent how much of a chance you have of connecting for a successful downld. So if you see a file in the search results with 4 stars, that means a high chance of connecting with them. If they only have one star then you will have great problems connecting to them. Remember also, trying to connect to those results with multiple users under the # column will make it easier to connect & chances to downld from more than one source.

As for viruses, ignore all files less than 1 MB (1,000 KB). Arrange your search results by size to have the largest at the top. Also, you can use the junk filter to filter out viruses. It's a dynamic learning filter & takes time to learn. Viruses take much longer for it to learn about. More information here WARNING: Viruses on network you should be aware of! (click on link)