If you are going to use a 2.5 HD, then make sure that it isn't larger than 4 gigs. If you want larger disks then you should use OS 3.5 or 3.9.
Use a standard 2.5 IDE-cable. There is a connector on the motherboard.
It is possible to use a converter to connect a PC-monitor, but it is unlikely that you would be able to use that set-up for gaming.
Best buy would be a scan-doubler.
I'd suggest that you get an accelerator, or at least a RAM-expansion, aswell.
Good luck!
