If you're running a 64-bit version of Windows 7 home premium or higher, you can certainly run a 3TB hard drive to its full capacity. You will, however need a UEFI-capable motherboard. There are several guides as to how to do it online. Simply search 'Installing Windows 7 on a GPT hard drive'. Also, if you are unsure if your motherboard supports UEFI you can easily find it by looking through the BIOS.
That's it LOL... I tried to clone my 1.5tb (win7 64) to the 3tb and use it and give my kid the 1.5 but I couldn't convert to GPT and clone, I found one software program that claimed to do that and people said it worked but it didn't work for me... so he got the 3tb cause I wasn't about to reinstall all my crap just for 1.5 terabytes, wasn't worth it to me.