Compatibility Formating 3TB Drives With GPT

I am planning to setup a windows 7 64bit based HTPC, and I have realized that I need more then 2TB of storage, so I am planning to use 2x3TB Hard drives, setup in Raid 1. Right now there are two ways I am thinking of setting it up, either with the 2x3TB drives in Raid 1 directly attached to the HTPC (sata3), or with the 2x3TB drives in a separate NAS drive, so I can make the media more available on the network.I read the thread here, and I see that I would need to format the drives as GPT instead of MBR, and I have some questions on how would work with my setup and if it would be compatible. If I put the drives locally in the HTPC, I would just be using them as data drives setup in Raid 1, the OS would still boot from a separate normal MBR hard drive. It has also been mentioned that you may need a EFI bios, which I understand is very new and few motherboards ship with this type of bios, or can even be upgraded to to it? Is this needed at all for using these drives, if I am not attempting to boot from a GPT drive? So my main questions are, if I install win 7 normally on a separate MBR hard drive on this AM3 motherboard, and then connect the 3TB drives, should I be able to format them as GPT with no issues, and setup them up in a raid 1? And then if I share them on the network, should other computers be able to access them with no issues? Also should they work fine in this dlink NAS listed below, and be accessible on the network as normal? Would I need to format them to GPT first in a win 7 computer, or could they maybe be formatted directly in the NAS?