I'm looking for a surround sound package that'll best match what I have.
This is what I've got to work with:
TV - A/V (RCA) with S-Video IN DirectTV - A/V (RCA) with S-Video OUT DVD-Recorder - Digital Audio OUT, Component Video OUT, A/V (RCA) with S-Video OUT, A/V (RCA) with S-Video IN (for recording)
We're also plan on getting a Media Center (one that can stream from your computer). I've seen receivers with USB ports but didn't know what all you could use it for.
David $700 is certainly not a lot, but you can probably do better than a Home theater in a box concepts out there. You may want to look at a Panasonic digital receiver XR55 or XR57 at about $250 - $300 plus a set of 5 speakers for the rest. Some Athena models have been recommended on the speaker web site. They may fit in your price range.
As for a media center, I have recently purchased a squeezebox. It is a device that you connect to your receiver and it connects to your wireless router (there is also a wired only ethernet model). It comes with software that let's you categorize and stream your music and internet radio to your amp. I haven't put it together yet, but as soon as I do I will put up a review for everyone else. It comes with a 30 day money back guarantee, so you won't go wrong with it.