HELP! I think I screwed up.

Alrighty short story of how dumb I am:

I go to try and upgrade my G50vt to a 9800m GTS. I read everything on the guide perfectly well, but I think I did something wrong formatting a bootable pen drive because now I can't get into Vista (thank god for ExpressGate, right?). I never typed anything to actually flash it, so I still have a GS.

Hanyways, upon booting from the flash drive, the MS bar comes up, but it reboots just shy of where I'm supposed to hear the Vista sound and then log in. I tried the "Last known good configuration" but that did no good.
EDIT: Safe mode bluesceens I think I need to restore.

So now I'm stuck!
Is there anything I can do short of a restore? I don't want to go through the hassle of all that. How can I undo what I did?
Aside from this I have some tech knowhow so don't hold back.

Thanks in advance!

 

Make sure that Vista's ReadyBoost isn't enabled on your flash drive - if it is, it'll use any remaining space on the FD.

Right click on the drive icon, then on Properties, then the ReadyBoost tab.

 

Flashing video BIOS........ dangerous stuff for some.

What happens when you try to boot with the USB not inserted?

Go into the G50's BIOS ( F2@ startup) and make sure that the boot order has HDD before USB, and then try startup again and see if that works.

Edit: As the next post indicated the current error

 

BIOS setup is F2

Edit: Also you're not likely to have success with a recovery... your best bet is to flash the stock BIOS back and try safe mode. If that works, probably just reinstall your NVIDIA drivers and try a lower frequency setting in the modded BIOS.

 

Yeah I've been able to get to the BIOS setup all along, and it does boot from devices, so that's a good sign. I have it booting from just the hard drive now.

I didn't actually change the 9800m yet, but they way I'm looking at it I think I'm just going to restore :/

Thanks for everyone's help!