Though I obviously don't know your friends and what they're like, I think when spending this much money on a system that it would be best if you didn't consider their opinions so much. If it fits your gaming requirements (which it may not I'm just saying), go ahead and buy it. This is a whole new computer, not a mouse mat :/
Looking at Overclockers UK it looks like you can build a decent system with a 560gtx using the AMD gaming PC base.