Computer does not restart after upgrading GPU, but can turn off and on

Here's the situation, I just upgraded my video card from a 9800 Pro to a 1950GT. It runs smoothly I believe with -0.2v on the rails max. However, when I'm installing drivers, xp, etc and let it restart, it will not restart. It will shut down, but then not display anything again. I need to force it to shut down by holding the power and then boot it up. I'm convinced that it's my BIOS which is the original version that was released with the mobo in 2003 which is too old. Two questions:

1. Is this a possible cause/solution?

2. Can I flash the bios just with a USB Flash drive or CD-Rom? I have no floppy drive.

I need somebody to hold my hand, I hear flashing the BIOS unsuccessfully = game over.

Any other input is greatly appreciated.

There could be a number of reasons XP won't shut down, but the most common is that ACPI is not enabled. Check this:
Start, Control Panel, Performance and Maintenance, Power Options Tab
Then click APM, Enable Advanced Power Management Support

And yeah, if you can instantly render your motherboard lifeless if you botch a BIOS update. Updating the BIOS is fairly straight forward, but if you don't follow the instructions to the LETTER, you can easily end up very, very disappointed.