I've said it before a few times in different threads. Beware of Tigerdirect Barebones kits.
The one listed above isn't too bad. Avoid their Sub $400 barebones kits like the plague.
Why? Here's a few reasons:
1) Outdated or Older parts, the processor in the link above is about 2 years old. It's a tried and true one, but a bit dated IMO.
2) Unknown brands of power supplies. Ultra's higher end stuff probably isn't bad. There are other parts I'd recommend over them though
3) Cheap parts. To get the prices down on the kits, they'll use cheaper quality cases and accessories
4) Rebates, they're fairly notorious for not honoring their rebates. I can attest to this.
If you want to build the stuff yourself (it's really easy, if you can handle a screw driver, read a manual, fairly handy - its one of those things you'll be proud of that you can do), pick out the parts yourself, or ask some forum members. Basically set your budget and lots of folks here can pick out the parts for you. There are hundreds of tutorials on how to build computers out there - check google and youtube.
I highly recommend building computers (if you're up to it) rather than buying a pre-made or having someone make it for you. It greatly increases your knowledge and understanding on how computers work. And like I said before, the self-satisfaction of doing it is the icing on the cake.