So first and foremost, here are the two cases and their motherboards specifications:
My brothers case:
I had better RAM than he originally had, but his case supports my RAM. You'll also notice that both cases support the same processors, so although I cannot remember my processors speed this should be irrelevant, if anything his case again should cope better than mine. So we switched RAM and processors.
We switched around our hard drives, kept the same DVD+RW drives, we moved my TV card into the bigger case, and put in a graphics card that had already been used in the case.
Anyway, I moved the now rebuilt version of my machine back to my room, switched it on...and that's when the problem started. The computer starts up, the fan whirs (on one occasion very loudly?) then there is no beep and no image is displayed on the monitor. I have also obviously tried the obvious and just plugged the monitor into the onboard graphics card.