What features are you most interested in? Wattage (most will prolly be so similar you wont notice a difference), video chip (ABT/Faroudja prolly your only 2 options in that price range), network capability obviously (I use optical/hdmi to connect from my pc to avr but network is nice too), # of channels, gui, audyssey, #of HDMI in/outs, decoders, scaling, deinterlacing...there are a lotta factors. Try to figure out what exactly what you want out of your receiver...so we can help you pick the best one for you. Take my word for it its better to measure 5 times and cut once. I made the mistake of buying/returning like 4 receivers before I settled on my current on. So take your time, figure out what all they can do, what you want it to do, tell us what you want, we'll help you out. Here's a tip, do some research on video chips that some receivers use (Anchor Bay chips, Faroudja...ect)...its worth getting a receiver with one of those. I notice a difference in the picture.
Your system is only as good as your weakest component.