OS 4 betas are for registered, paid-up, iPhone developers only. You can only develop on a Mac. Therefore Apple only spend resources on making the betas install correctly on a Mac.
That said a paid-up developer would have access to the notes that go with the current release that offer a method to backup beta 2 devices (and I suspect therefore install) on a Windows machine. As the OP does not know what this is it appears he is using illegally obtained software.