From what experience I've had with Dell units, they tend to be non-standard components designed specifically for Dell, and are non-interchangeable with standard units. Thus you would probably be limited to upgrade within the Dell tower, but without having the system board out of the tower in front of me it's hard to be absolutely certain! Meanwhile what you have ordered seems pretty capable, and without further details on the PSU hard to advise further. If you can change the PSU selection before delivery I would recommend that...