Yes, it really comes down to wants against needs. On the other hand, I'm majoring in comp sci and engineering, so maybe a new rig would be beneficial there. Though simple programming and what-not can be handled by my notebook. Edit: Because wants and desires are essentially the same thing :/
I would think that building your own pc would be a benifit in the comp sci field, I'm not sure that would be concidered experience, but it IS something that would be valuable. Depend's on the exact job I guess.
I'm looking at a new Laptop ( not just for gameing but I want one that will also ) They are not cheap, but I need a laptop for my work... dang hard to lug around a desktop.
Look at how much you are going to play now, is it worth it now OR is it something that could wait til you get out of college and get a job? Then again it depends on how long you have left in college. I'm going to take a guess and say at least another year? if not and your just finishing off with summer courses then no, I would wait.
The benifit's of a desk top gameing are great, I like my 360 & ps3, I wish my laptop would play games, but truth is I would have to delete way to much to even play Morrowind. ( including my work program)
I can't give advice on building a pc, cause I know nothing. BUT when it comes down to it and you either by "X" part now and can play now OR get the better version next week or the week after....wait. JMO