Not sure why you could not install on separate drive. I have four 500 gig HDD's and it is installed on the second thus I was able to set it as a dual boot on two different drives.I installed as a dual boot using 2 separate drives, first unplugging the Windows 7 SSD drive then installing Windows 8 on the other formatted spinner drive. After Windows 8 installation I reattached the Windows 7 drive.
Only drawback is I do not have a boot order menu but have to use Bios boot order menu options (F8) on my Asus mobo to boot into either Windows 7 or Windows 8.
As others have alluded to the installer will let you choose a separate partition on the same drive but not a separate drive.
I'm going to try that, as I've said in another post, using the regular x64bit preview the apps stopped working after about an hour or two, and the resolution is well above 1024 x 768. I'll report back if that makes any difference.Clean installation Multiboot with Windows 7 Ultimate and Windows 8 7989, all 64-bit.
I recommend using the WindowsDeveloperPreview-64bit-English-Developer version (the largest of the available downloads). The applications work with this version.
The installer functions in the same way as Windows 7, so should cause no problems. I installed from a USB key, created in exactly the same way as those for Vista and Windows 7.
Dual boot with Windows 7, I simply replaced the Server 2008 R2 installation I had running on a second harddrive with Windows 8. Funny though, I get the new boot screen, and it boots into Windows 8 (I changed the delay to 5 seconds), when I choose Windows 7, it reboots (as in I see the bios screen) and then boots straight into Windows 7. Maybe it is the crappy Alienware bios messing up here, but I thought it was funny in any case, it just adds about 20 seconds additional boot time to Windows 7, just as if they want me to run Windows 8, which in this way boots up much much quicker then 7