I have a LCD P2370MS with ATI XFX Radeon 5770 on a I7-860 and Windows 7-64bit is working fine, the problem is I am not able to see the first Post screen. I see only "Loading operating system" then windows starts.
You probably have it set to quick boot. Push delete a bunch when it restats to see if you can enter the BIOS. If not, you will have to reset your CMOS jumper pin to clear the BIOS memory. Check your motherboard manual for instructions.
It may be due to the connection you have selected. If you have connected the monitor through DVI then it takes around 3-4 seconds to switch to that connector and in that time your POST seems to pass. You can try to enable boot logo from BIOS that might give you some time to see POST or simply start hitting Del when you start your computer with some luck you should reach BIOS Setup.