Its very hard to get good, reliable advice on a power cord. Even if you have 2 systems that are exactly the same, your AC won't be. Given that, its really mandatory that you audition power cords in your own system.
If, for some reason, you have to take a chance buy something without being able to demo it, I recommend you consider ESP and Richard Grey power cords. They both have a very good reputation for working well in just about any system.
Rlwainwright,
I have to point out that your post is not entirely accurate. You can, indeed, buy a power chord. There's a cable company naimed Chord. If you had to guess, what do you think they call their power cords?