Message 73003 - Python tracker

I'm seeing the same symptoms that are described in issue 1543 with the
2.6b3 MSIs. Namely, when you run one of the MSIs (either 32-bit or
64-bit) then the other will refuse to install. This is on XP Pro x64 SP2.

python-3.0b3.msi and python-3.0b3.amd64.msi exhibit the same problem.

Having 32-bit and 64-bit version coexist makes it much easier to build
extensions for and test on both versions at the same time.