which require even more fedora10 packages.
And by the time you finish the dependencies, its now more of a FC10 than a CentOS5.3. To resolve your issue, as pschaff stated
Run Fedora, either on the bare hardware, or in a virtual machine.
The reason why CentOS is CentOS is because of the packages that it uses, not the latest and the greatest but backported ones for the main purpose of being stable. The reason why Fedora is Fedora is because of its cutting edge packages. If you need those cutting edge packages, then it is more suitable to use Fedora than to modify Centos to be more Fedora like.
Think of this: What happens when your modified CentOS breaks in 2am? Where would you seek help? CentOS forums or Fedora forums? I will not be surprised if you would not be getting any help from the CentOS forums because nobody can replicate your system because in order to do so, they must also modify the packages that you have modified, which will make the system less CentOS. If you are going to seek help from the Fedora forums, they might say "you have a CentOS system, please go to CentOS forums for help." I hope this cleared things up on why pschaff suggested that you use Fedora.
I am just curious, why do you choose CentOS over Fedora?