Win2k3 convert to dynamic grayed out - GPT and me

I decided to add another drive to an external vault that's attached to my backup exec system. It's used as an intermediary for disk to disk to tape backups and was getting a bit full. (1.9TB) So I added a disk to the array, let it rebuild and then went into computer management. Then I found that all options for adding or changing the drive were grayed out including "convert to dynamic", "convert to GPT", etc. This was puzzling but after some reseach I found out that I had hit a 2TB barrier that's caused by the old Master Boot Record (MBR) partitioning scheme. The solution Microsoft proposes is to go to the GPT paritioning scheme (GUID partitioning) which scales up to 2^64 logical blocks in length.
http://www.microsoft.com/whdc/device/storage/GPT_FAQ.mspx

Of course the hitch is that you have to wipe out everything on the drive before you can convert to GPT. Even if you try to do it from diskpart you'll get a "The disk you specified is not empty." "Please select an empty MBR disk to convert." So after whacking everything on the disk, it let me upgrade the partition scheme to GPT and I was then able to utilize all the space on the disk.



I have no idea how the performance is affected when you go from MBR to GPT as I haven't been able to find any reviews online. So far I haven't noticed any decrease in performance so that's good. Oh, and in case you're wondering, Symantec Ghost Solutions 2.0 and higher support ghosting GPT partitions.
http://www.symantec.com/business/products/newfeatures.jsp?pcid=2247&pvid=865_1