Jonathan,
I'm interested in a similar setup on a similar budget. I was going to use two active monitors, but I didn't like my options. So, now I'm looking to do two bookshelf speakers, a powered 2-channel amp and a subwoofer. This system is going into an apartment at school I'm getting next year.
So, I'll share with you a bit of what I have found and maybe we can put our heads together and figure out some good options!
Rotel has the RX-1050, which is a 2-channel 100watt @ 8ohms. It's gotten pretty good reviews, but I have yet to find a place to demo it. I can't find MSRP on it, and the AudioReview reviews state everywhere from 400 - 800 bucks. I can't find a real price on it.
NAD has the C740 Stereo Receiver. 2-channels @ 40watts. MSRP is $499. That might be more affordable.
The Monitor Audio S2s I'm looking at have an RMS of 100watts, and the NAD only makes 40, so I sent MA an e-mail asking them their thoughts about that. I guess I could start with the 40 and then get a seperate amp later on. You should look at the MA S2's, but you might want to add a subwoofer with them if you like a good punch because these are just little bookshelf.
I'm interested how others will respond to your question.
Also, register! I'm new here and like it a lot.
-Chad