Yes, you can boot from a GPT drive in Windows 8, and all your parts should be capable since it is a new machine. HERE
is a tutorial on how to convert -- you need to delete all of the existing partitions on the drive and then repartition with GPT. You need to boot from your install disk to delete the partitions since you have an OS on the drive already. You may be able to get by with just doing a new installation and selecting custom and then deleting all partitions, which works in Windows 7 but I haven't tried it yet in 8. And all data will be lost so back it up first.