Tap F8 (usually) as you switch on and using the cursor keys select Disable automatic restart on system failure and press enter.
This will allow you to read the Stop Error Code.
You could also try Last Known Good Configuration as well.
Laptops tend not to have this but with a desktop, tap F2 (usually) to go into the BIOS and check the temperatures.
Also if you have an external HDD connected when you boot up or a DVD left in, then they should be removed as that can confuse Windows as to which to boot from.
If you can boot up into Safe Mode with Networking, that would tend to point to your Graphics.
If you can boot up okay in Safe Mode etc. and the temps don't display in the BIOS, then download HWMonitor which will give you that info - or you may be able to copy it across from another machine.
http://www.cpuid.com/softwares/hwmonitor.htmlAlso if Safe Mode with Networking works okay then go to the computer or motherboard support site and download the Chipset/Video drivers, but the Stop Error Code will better pinpoint the problem.