The questions I need to ask are:
Is this rig good enough for current gaming to a highish standard?
Is the HDD the right form for the mobo as I dont get the form connections for mobo and HDD?
1. As long as you put a good graphics card in, yes. It'll do well in the large majority of games. Your CPU might hold you back slightly in CPU-intensive games like Skyrim, BF3 multiplayer, or MMOs.
2. The SATA connectors are standardized. Since the drive is 3.5" it should also be easy to mount in your case.
PS: You could go with a slightly weaker PSU, something in the 550W range would still run just about any combination of CPU and single-GPU graphics card out there. Only do this if you can actually save some money and still get a quality PSU.