Win7 on ASUS P5K-VM won't recognize any hard drives, no matter what !!

You'd have to SysPrep the HD from the other machine to expect Win7 to start up on the new machine.

It may have detected the problem HD because you cabled it correctly when adding the second HD. Were these master/slave on IDE ribbon?

Finally, when you installed to target HD it configured a dual boot with Win7 using the System boot files on existing Win7 so that it wouldn't start when you removed the that HD until you ran Startup Repair to write the System Boot files to the target HD.

If you'll post up a screenshot of your maximized Disk Mgmt drive map and listings, we can look it over for you closer. Use Snipping Tool in Start Menu.

I agree it may have been "master/slave" issue. I was using Cable Select jumpering on all drives while doing this. The one thing I didn't try to load Windows conventionally was to jumper the drives as Master/Slave and re-try.

The box I was doing this on is gone already, sorry I can't post a screen shot of the Disk Mgmt map. It wouldn't show much anyway as I removed the "helper" hard drive as soon as possible, even deleted the Windows partition from it.

You're correct about the dual boot configuration too, it gave me a choice of which Win7 installation to boot to a couple of times...

Last follow up, definitive proof tonight of the cause of my issues...

Whole different rig, two hard drives, on IDE, one SATA both installed and jumpered properly, neither seen by Win7 when looking for a place to load the OS, went back to "Repair" screen, chose tools, used diskpart to clean both disks, which were marked as 0GB free, and Dynamic Disks in diskpart. After simple clean command(instead of much longer "clean all" command), booted to Win7 install and both drives now showed up as unallocated and available for installation.

Lesson learned, formerly spanned volumes, marked as "dynamic" can not be seen by Win7 during installation and MUST be cleaned of that info before Win7 will see them as available for installation.

Thanks to everyone for the help, without the pointer to diskpart, I wouldn't likely have solved this problem.

Glad it helped. Please mark the thread as Solved at top.