Don't use copyrighted music. Try something like Stock 20:
Stock20.com creates high quality music for media production. If you create a free account, they will give you a $7 store credit (which will get you one free song).
If you use my referral link (below) I get one free song, you'll get a total of $14 credit.
1) Click this link, then create a free account (it takes about a minute):
2) Your new account will automatically be credited with $7 (enough to get a free song).
Then you will get an additional gift certificate by e-mail, just for creating an account. That's a total of $14 in free music.
As to the slide show programs, there are a few out there that should do the trick. I quick search will produce lots of hits.