Upgrade Hard Drives?

I have read quite a few posts and also talked to Apple Support - but I am still confused.
I have a MAC PRO purchased in October, 2007. It has a 500 GB hard drive in bay #1 for all my programs and a little data. I also have 3 hard drives in bays #2, #3 and #4. These three are 750GB each and are used only for data files. My operating system is MAC OS X version 10.4.11.
My question is, can I replace the 3 x 750GB drives used for data storage with either 1.5TB or 2.0 TB drives? (I understand that the WD 2.0TB drive is slower).
Or, is there some sort of max amount of internal storage allowed based on motherboard or something?
MAC Support said they could only say go to 3 x 1TB drives. But according to some posts, I think some people have tried larger drives OK.
Any help will be much appreciated.
Thank you.


I too am looking to upgrade the hard drive in my Mac Pro. I currently have the original 250GB drive that came with my machine as my primary (for apps and user account stuff), a secondary 250GB drive (for my actual work), and a 500GB drive in bay 3 that I use as a Time Machine drive.
I was thinking about adding a 1TB drive as my primary and move the 250GB out as a work backup/catch all/scratch disk. I'm looking at the WD Black 1TB, but I'm concerned about reliability. Are 1TB drives a lot more reliable now than when they first came out? If reliability is more important to me, should I just stick with a smaller 500GB drive since I probably don't really need a terabyte for my primary?