Can't install Office 2010 (any # of bits) in Windows 7 (64-bit)

I've just installed both versions of Windows 7, 32-bit and 64-bit, through Parallels 8 on a Mac running Lion. Next step: installing Office 2010, Home & Student Edition. It works in 32-bit Windows 7, but I only tried this after it failed in 64-bit Windows 7, which is the OS I'd prefer to run.

In 64-bit Windows 7, the Office installation disk does not autorun (but it does in 32-bit Win). When I navigate to the setup.exe files (for 32-bit, 64-bit, and apparently 86-bit), clicking on them always results in the "Not a valid Win32 application" message and I can go no further. Clicking on the autorun file results in Notepad attempting to open the file for editing (FYI, Notepad fails because it says the file is too big).

I selected the same options for both Windows installations. What can I do to make 64-bit Windows 7 properly install Office? Why isn't it working?

Thanks!

I identified the problem, and it was related to Parallels rather than to Windows. Mysteriously, in the Parallels "Devices" menu, my DVD drive had been disabled (but the DVD was still visible within the Windows interface). I re-enabled it and was able to install Office no problem.