Riz, the mac mini has just refreshed and if it weren't for it being really fucking expensive here I'd be recommending that. The Dell Studio Hybrid is kind of underpowered in the graphics dept if you're wanting to play games. I am not familiar with your level of pc bits knowledge, but if you are not ofay with the whole shebang and want something with a warranty check out local computer stores that don't look shitty. Most pc stores will put a pc together for you using the bits you specify, and so long as they put it together in the shop they will give a warranty (usually through some third party support line).
And yeah, I really wouldn't go with AMD cpus at the moment either. Intel have their shit sorted right now. LGA775 isn't going anywhere for the short-medium term, the i7 stuff is top line premium shit, and the i5 stuff isn't out properly yet.