PSU will likely be... um... less then awesome. I would consider a bare-bones, if you can stomach the idea of piecing in the optical drive, hard drive, ram and CPU. You'll likely get a better end product... and you will know what you have. All in all, though, the dell will probably be enough for your needs and it is easier then piecing together one.
Go with the dell. Just know that the PSU will not likely be enough to power much in terms of a descrete video card.