When you don't have to buy the OS, you save a lot of money. So I spend it on more nice stuff for my computer.
I have to get a wireless N card too, but that doesn't really matter, my step-dad got a N-Router, and if it is there might as well, right.
The trick is to buy a refurbished system and then add some goods to it. The only thing I had to add to it was the video card and 2 gigs of RAM(Just for bragging rights, I don't think anyone needs 4 gigs of RAM))