I have XP installed on an old pc. Will Parallels run with the os on an external drive if I pull the drive out of the pc and put it in an enclosure?

Don't think so. You can put the paralells transporter tool on the PC and "clone" your PC to a disk image on the Mac. You can have that disk image reside on an external Drive (probably) ...but I don't think you can run a standard Windows system from an external HD

I could be wrong though.

I can verify that a clone of Windows XP virtual machine runs for me on an external Firewire drive. Parallels is on my Mac OS X system disk, in the Applications folder, and the original Windows XP virtual machine is in the Shared user of that drive. Whenever I launch the virtual machine on the external drive a warning comes up that says not to dismount the drive while Windows is running. I think it would run if I deleted the original virtual machine, because a selection window comes up when I launch Parallels. I'm using Parallels 4.

Thanks for the reply. I knew it wouldn't work using Bootcamp. I need to run a piece of windows software on a Macbook so it can be taken to a class. I can't haul the pc around but a laptop and external drive would probably work. Would the disk image be enough to run the software if the software was installed on the pc and then put in an external case?

I've heard it can work booting Windows from an external, but you need to jump through some hoops, and remove the internal drive to do the install. Windows resets the USB buss during startup, at which point the boot process stops of course. The Windows installer CD must be modified to make Windows boot from USB. You will also have to install the drivers from Boot Camp.

Here's one article on it.

Since your PC installation doesn't have the modification it won't boot, plus Windows will probably complain about booting from different hardware. Your best bet is just run Parallels on the MacBook or do the Boot Camp way. I don't know if Parallels will run off of a cloned drive im age, just because of the authentication crap, not because the clones don't work. Cloning to a Boot Camp partition will probably have the same authentication problems.

Firewire is a no go.

Thanks for all the infp. My copy of XP is a single install license and it is on Gigi's iMac. I didn't want to have to buy another copy of XP just for the laptop. Microsoft might give me another license key if I removed it from the iMac and put it on the laptop. I have an OEM copy of XP Pro that came with a Dell computer but I don't know if that would work on the laptop.

Here's a possibility. You don't have to install Windows. I think MacGizmo's tried it out.