That's not the one that you'll need, and it'll depend on what kind of G5 you have.
If you have the (LATE 2005) DualCore 2.0,2.3, or Quad 2.5,
you'll need to search google for ASD 2.6.3
If you have any of the other G5's (June 2004) Dual 2.0, Dual 2.3, Dual 2.5,Dual 2.7
you'll need to search for ASD 2.5.8
You'll find it on google if you search hard enough.