Python version 2.6 required, which was not found in the registry
For me this happens on a 32 bit system with activepython installed.
It seams that the regs are not in HKEY_CURRENT_USER so here is what I do to fix that.

Export the "Python" section under HKEY_LOCAL_MACHINE -> Software
Open the export in notepad notepad. Replace "LOCAL_MACHINE" with "CURRENT_USER"
Since I have 2.7 installed I also had to replace "2.7" with "2.6" (make sure that you do not affect the path which points to the installation of python).
Over write the reg backup and run it.

Now if you run the installation of whatever package you needed it will find python.
This helped in my case but be aware that it might not work for you.
Can't download any python Windows modules and install. I wanted to experiment with scrapy framework and stackless but unable to install due to error "Python version 2.6 required, which was not found in the registry". 
Trying to install it to
Windows 7, 64 bit machine