I just went and got a second hard drive for my G5 (Seagate Barricuda (ST3120026AS) and the installation was easy.
For those G5 owners, this is a quiet and fast drive, and installation is easy. A great addition.
Jut thought I'd mention it. =)
IIci / IIsi / LC475 / Radius 81/110 / 7200/90 / UMAX S900 / UMAX S900/G3 / G4/466 / G4/867 / G4 1.25 MDD / G5 Dual 2.0 / Powerbook G4 15" 1.67 / MacBook Pro 15" 2.2 C2D / MacPro 2.8 Octo + Dell Mini 10v Netbook running OS X 10.6.2 / Apple TV 2 / iPhone 4 / iPad 2