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