What I would do is as follows but you may or may not choose to go this route:

Yamaha HTR-5760 - $365 delivered (niceelectronics.com). Crap shoot here as they say the USA warranty is included but Yamaha does not list them on their website as an authorized dealer. You can go with the RX-V650 for $10 more.
Ascend Acoustics S23-2000 system - $894 delivered from AscendAcoustics.com. Traditional black speakers. Of course, if you should choose you can buy my nOrh 4.0 ceramic video package for $500 plus shipping (more detail at HTF) and that will save some money, enough to go up to a either HTR-5790 or RX-V1400.
Finally, one of the best subs out there, the SVS 20-39PCi goes for $599 plus shipping. I have the CS version of this sub in my system now. Fantastic sub that should be able to handle most anything you throw at it. Not the be all end all of $600 subs though you would be hard pressed to find something that will beat it for HT. The HSU VTF-2 is another worthy contender.

What room size (dimensions) will this future system be going in? Additionally, any openings into other rooms and, if so, what size are they? I hope you enjoy your future system, whatever it may be.