Well, one question is what do you need the desktop for; and do you already have a desktop, or are you planning on building one?
If you are planning on getting a desktop for gaming, and you don't already have one, that will set you back a few quid.
Really, if you are looking to add some gaming to your room, and your laptop can't do it, I might think about getting yourself an xbox instead, easier and cheaper if just for the sake of gaming.