Do you remember what driver version you had installed in the windows environment, if so see if that’s the same driver that loads in safe mode if it is then there are a few things you could do.
1--- Have the power supply tested and make sure they can test it under a load. (Just to be sure and eliminate this as a problem)
2--- Run a full virus scan in safe mode.
3--- Remove the card/Inspect and clean the contacts if they look tarnished this could be a problem on the power side of things.
4--- “Make note of the driver version used in safe mode first” Enter safe mode and uninstall the video driver/reboot to normal windows (if it will I think the chances are good it will if it has to do with the driver) and let windows install the driver for the card.
5--- “In the event step 4 works” then you can reinstall the drivers you want and see if the problem comes back. If it comes back then you can revert to an older driver and go from there.
I don’t know if you got them yet but there were some hefty update for windows Tuesday, I haven’t heard of problems with them but it’s possible the updates or something else that happened in the last few weeks caused some driver corruption. (Power spike maybe or just windows getting stupid)
One easy thing you could try is disconnect the power cable to your Rom drives and floppy if you have one and see if windows will load. (If windows loads after the drives are disconnected then I would seriously look at the power supply, I would look at it anyway but this is easy enough to try)
By chance have you installed any new software or hardware in the last few weeks?
As for Antec I’ve had good luck with them for the most part but there are bad one’s out there.
I just want to be sure on the power supply because what I’ve seen happen when it’s not caught early is the HD is next to go and I don’t want to see you lose the HD.
You could check the refresh rate (if you can get to it) also, I have seen this reset to a rate the monitor could not handle and this same thing happens. (What reset them I don’t know but I’ve seen them change for no apparent reason)