If I change the harddisk with parallels installed to another iMac with different specifications, will parallels and my current guest OS still function? Thanks in advance!
If you physically move a hard disk to a different machine? That depends on the machines. If that HD is not your startup disk, and the new machine has enough RAM, it should be fine. If the new machine has less RAM than the old, you may have to adjust guest allocation. If the disk you are moving is your startup disk, and the new machine has enough RAM, and OSX boots properly, then again, it should work. If it doesn't, you can reinstall Parallels, which will not touch your VMs, reboot the Mac, and it should work. Note that I haven't tried it.
Rather than take chances just make a backup of the Parallels virtual machine. After you've migrated the disk to the other machine, try to run your original vm. If it fails then all you should have to do is re-install Parallels and then try running your vm again. If that fails, then delete the vm and use a copy of your backup. If everything fails then you can still put it all back into the original machine and hopefully everything will continue to run. I don't know if this is true for OS X, but many Unixes make installation parameter choices based on the hardware the installer discovers so if the two systems are sufficiently different this disk swap may never work quite right. But but having a backup of your VM is never a bad idea.
