Can't finish installation of 5.0 on Win7 64 bits (no replies)

I need to install an instance of MySQL 5.0 on my Win7 64bit machine. go the 64 bit install, doing a clean installation, but after the first part of the setup is done and I get the dialog "Configure MySQL now", nothing happens... so I ru MySQLInstanceConfig manually, do a detailed config, and at the final step, it can't write the config file. the Write Config file step shows a red X.
I installed 5.1 without a problem, but need 5.0 for hosting compatibility issues...
any idea?