I really don't like the idea of overwriting my main Win7 installation before giving it a try elsewhere. That leaves me with two options.
Currently my system has three internal disks: an SSD with Win7 on it, a 2TB HDD for data, and a 1TB HDD for screen captures. The 1TB disk is out, because I don't want anything on it. The 2TB drive is currently in one partition, so if I want to use it for dual boot I'd have to repartition it. Either I have to move about 800GB of data off it and back on, or I shrink the partition and create a new one at the end. That would work, but it does mean I'm installing Windows 8 on the slowest part of the disk (near the end).
Alternatively, I have an old 500GB drive that I removed from the machine due to its tendency to vibrate on occasion. I could put that one back in (assuming I have enough SATA power cables left) and install Win8 on that.
Either way, it's going to be a step back from using the SSD as the boot drive, which is hardly an optimal solution. I also don't like dual booting for evaluation because I tend to end up using the old OS because that already has all my apps and settings.
What was MS thinking releasing a technical preview OS and not making it compatible with virtual machines? Don't they realize that that's how us techies evaluate stuff nowadays?
EDIT: I tried it Windows Virtual PC 7 (with the x86 edition, obviously) and got the same HAL_INITIALIZATION_FAILED error.