Actually, it's a not-BIOS think. The Extensible Firmware Interface is a replacement for BIOS, with the intent of overcoming limitations of a standard that was set up decades ago.
The easiest way to find out if the mobo is efi capable is: READ THE MANUAL. Or even the manufacturer's description. There are very few EFI mobos to date. What model motherboard do you have?
You could look on the box for the picture on this page: http://en.wikipedia.org/wiki/Extensible_Firmware_Interface.
No picture, no EFI.
Edit: I was wrong; some motherboards can support GPT when running Windows 7. You can't boot from a GPT disk, though.
Again: I'll be darned, you can boot with a BIOS boot partition. Why do you want to use GPT - got drives larger than 2 TB?
Here is a poster with some experience: http://www.rodsbooks.com/gdisk/bios.html