So I got a Fujitsu Esprimo p2540 for free because I do IT work at my school and we didn't need it anymore so I could keep it. I want to upgrade it just for fun but I'm not that experienced. It has a Pentium E5200, a geforce 9300 ge 256mb vram, 3gb of ddr3 ram and a max 300W powersupply. I want to buy a used core2quad q8300 and a nvidia gts 450, maybe the msi one. I don't think the powersupply can handle that but I don't now if it is replaceable. Does a full atx powersupply fit in there (the case seems quite small)? Also the powersupply is mounted to the roof of the pc. Please tell me if there is a possibility of replacing the powersupply with a better one and if you have any recommendations about to what hardware I could upgrade please tell me.