Hello,
I just asked the same question of this panel over the weekend and receeved a positive response. I purchased the WD 1 TB Internal HD from Best Buy and installed it yesterday. It works like a dream and the installation was very easy. The G5 User Guide gave me everything I needed to open the side panel, locate the 4 spacer screws, screw them onto the sides of the drive, insert the drive, attached the cables and them partition the disk. Up and running just fine. (Now, unfortunately I bought my drive BEFORE they reduced the price to $299!)
Regards
Doug