Alright, tried it again this time on XPpro64, with another drive of the exact same model. Install was successful and zippy - something like 15 minutes. So there seems to be a weird loop that the installer gets itself into under win7.
I found another weird thing. If you use maya navigation style you can't subtract from selection since subtracting is under alt (with maya navigation style alt + left click = rotate view). If you switch to maya adding/subtracting style you loose ability to select loop of polygons by shift + left click ( shift + left click =…