Jdoris - make sure to get a decent USB cable and try to avoid going over 15 feet (the length USB begins to drop data). Kimber makes a very good cable for about $50 U.S. (6 foot). I haven't listened to a lot, but I didn't really hear much difference between the Kimber and cables in the $400 range. Rip your CDs using Exact Audio Copy (EAC) if possible (PC only), and try to use a player that supports FLAC since it is the most used hi rez format out there (iTunes does not support it). ComputerAudiophile.com has lots of great info for everything you may need.
Sgr - I'm using Nordost cables and an Isotek G2 mini-sub power conditioner. I haven't tried other cables with the PWD but went through a handful with my other DAC. I'm pretty happy with what I'm getting and feel no need to upgrade (yet anyway). I am considering a battery pack power upgrade to the DAC if I find someone who does them with good results - the AC in my house/neighborhood is just atrocious. I'm investigating an all battery powered system at the moment and trying to find the right amp/pre-amp before I jump in with everything else.
One thing I have noticed is that the shelf I have the DAC on is getting a lot of low end reverberations. The PWD is a large unit and when I put my hand on it, I can feel the top of it vibrate with the music and wonder what affect that is having. Obviously, I need to get my components moved to a less vulnerable spot. But I'm going to get some Vibrapods or other isolation disks and make sure the shelf isn't transferring vibrations as well.
I'm having fun experimenting with hi rez files (from my computer until the Bridge is available) and I really like what I'm hearing - especially vocal jazz and classical. I love the convenience of HD Tracks ($15 for 24/96 albums - sweet!). I so hope more stores, labels, and artists follow suit and start releasing their back catalog in digital hi rez. There's little reason to not have it as an option these days.
Have a music filled week-end everyone!