Im building a small sound system in my den. Its gonna consist of 4 bookshelf speakers and a sub (with its own amp).

I heard many good things about the Yamaha receivers and Im going to get one of those as the sound they put out is really good. The cheapest Yamaha runs for on sale now $229 and says its 100w per channel. Power wise, what type of receiver should I be looking for in the Yamahas for this type of STEREO sound setup. Again, its gonna be a 4 speaker stereo setup not 5.1 etc. My budget for the receiver is $500canadian or so.

Please help guys thanks