Can't save to new hard drive - GPT Partition

Hello,
I have a brand new hard drive. WD mybook 1TB. when i plugged it into the USB port, my computer, running on windows XP, recognized and installed the hard drive. yet when i go to save a file, no letter is assigned to the external hard drive. I have tried right clicking my computer, then going to manage. From here i went to storage, disk management. It labels the hard drive as Disk 1, basic, 931.51GB, online. in the right hand column there is a blue bar above the information box, and within it states: Healthy(GPT Protection Partition). When i right click here all options are unclickable except for help. What do i do so that i am able to use my brand new hard drive? Any help is appreciated.

Thanks!