Seems you forgot to reinstall Windows 7 from the DVD. Since it's a new mobo the activation will probably fail until you convinced Microsoft that it's a retail version and the old PC no longer exists. If it happens to be an OEM version, they will probably charge you for a new license code.
Booting up my HDD with a tone of new hardware; mobo, RAM, PSU, CPU.
Computer runs fine
Starts loading OS
Gets down to 'Loaded: systempnp.sys' and BSOD's with little to no information. people say that it's CDROM.sys (the next one) that fails to load.
Cannot boot to safemode; only system repair which hasn't helped much other than the command prompt.
no longer have the old PC to test the HDD in
Windows 7 64 bit