I already have 5.1 Boston Accoustics speakers, a PS3, HD cable box and 1080P TV, iPod, and now looking for my first ever receiver. It will be used for everything, from music to movies.
For the same price here in Canada, Im trying to choose between Onkyo TX-NR509 and Denon AVR-1612.
I'd go with the Onkyo based on past experience with their receivers. They seem to be built a tad better and easier to operate. Both are decent receivers and you can't go wrong with either, really.
I recommend you compare how these 2 receivers sound with your speakers. You should also see if you can find other comparably priced models to check out. It's all about which receiver/speaker combo sounds best to you.
Having auditioned the Denons, and being the owner of 5 Onkyo AV receivers including the NR5008 at present, and ordering an NR5009 when it comes out, I'd hve to recommend the Onkyo. Audio quality is much better with Onkyo, and generally you get more features per dollar with Onkyo over Denon.