Itunes 4.7.1 won't install, anyone got an answer?

hi, I have downloaded Itunes 4.7.1 but it won't let me install it, this is very frustrating as I cannot use Itunes music store without it. When I get to the 'install' window the installer displayes 3 checkboxes that are unable to be checked, these boxes are
- Itunes
- Ipod driver for mac osx 10.1.5
- Ipod driver for mac osx 10.2.8
at this point I have completed the stages 'introduction, read me, license, select destination' and am on 'installation type.' The install and easy install buttons are unselectable and only the'go back' button is able to be clicked.
I am trying to install this on a dual 2.0ghz G5 with 1024mb of ram, the installation is on the 'hard drive.' Anyone have any idea how I can get this to install, any help is greatley appreciated.

Carl

Do you have iTunes already open? or anything that hooks into to iTunes if so make sure you close all those programs down

I had a similar problem trying to install iLife04 ... synergy was open and the installer refused to install ...

nope, that don't work either, the installer is still keeping the install and quick install buttons locked, even when I have closed ALL programs on the G5. Hopefully someone can come up with an answer because this is driving me mad.

Carl