Can anyone help me?

I'm attempting to do a clean install on a Dell Precision T3400 with Windows 7 64 Bit OEM, but cannot complete the sequence.

It goes through the entire installation sequence, restarting a couple of times. It gets as far as commencing the "completing installation" sequence - making what I think this is the final reboot - and then hangs. I think what should come next is the bit where I enter information for first time use -  time, date, location - computer name etc. I never get this far though.

I have not upgraded the BIOS. It was previously running Windows Vista - but the disk has been wiped - so not sure if I can update the BIOS in this state.

One other thing - I have swapped the graphics card. The monitor works fine during the initial installation sequence.

Any suggestions?

Thanks very much for reading.