To begin with, that's a pretty stout system... nothing lower end to it.
First- your speaker interconnects can be simple 12 or 10 gage speaker wire. You might have to check if 10 gage fits your receiver, as most won't. Please like
www.axiomaudio.com, parts express, or even your local Lowe's home improvement center carry excellent products. If the receiver doesn't take 10 gage (and you are mentally set on 10 gage), you can pick up some banana plugs from the same places for the fit. 12 gage will be perfectly fine for up to 50 foot runs. The pre-made interconnects are nice to look at, but really won't give you any better sound quality than straight wire.
A power line conditioner is a debatable subject. If your plasma has a fan on it, you'll want to use a conventional UPS like you would buy for your computer. Just make sure the model you pick uses battery feed to the plugs. Cheaper systems siphon off electricity to charge the battery and only help in case of a power outage.
I don't really think you would need an upgrade on your DVD player at this point. The Samsung picture is pretty awesome on the HDMI out (I have an HD-941 feeding a Sony 42 inch RP and an HD-950 feeding a Mitsu big-box). I'd just sit tight and wait out the format war before moving up.
