Thanks, Slip. I kind of figured I was using a lower-end PSU.
If I were to upgrade my PSU, what would I need to know?
You can never go overboard with a PSU.. Even if your system only needs to use 400w, you can still put in a 1000w PSU and be fine. You just need to make sure all the connections are there, which since you're using a low-end assembly line PC PSU they will be. Open up your case, look at all the leads from PSU to your various components and compare them to whatever new PSU you're looking at, as long as they're on the new one, you're good to go. I use OCZ and would recommend it.
If you do upgrade your PSU, don't pick any of those cards, no need to.. If you decide to replace your PSU then pick a new card too.