" I also purchased an NVIDIA graphics card but this was too large to fit and had to be sent " " Is there a way of checking compatibility for sound card, graphics card and other hardware before purchase "
The best way and the way most of us check, is to download the manual. You don't have to go through it with a fine tooth comb, but most of the essential information is on the first few pages.
As to the graphics card. Unless you bought the wrong type of graphics card ( pci > agp > pci-e ), then it would be the case that would determine what size of card you can use.