Parallels doesn't care where you have your Windows XP dirve image, so external drive is fine.
With Boot Camp, you can only do Windows on the internal drive.
With Boot Camp, you can only do Windows on the internal drive.
I can also perform heart bypass surgery, but it takes some work and time.Not true. You can run windows on an external with Boot Camp. It takes some work, but it can be done.
unless the external drive's connection speed is drastically less than your internal. a USB 2.0 external for example wouldn't be nearly as fast as just running it off your internal SATA drive even if on the same volume.BTW... Not only can you run your Parallels Virtual Machine on a external drive, for better performance you should. Running your vm on a separate drive dramatically increases performance as their is less thrashing for the disk on the main system.