Solved! 2 OS on one laptop.

[bi66al]

Hello,
I have a good laptop HDD with XP installed. MY internal HDD has Vista as OS. Can I buy an external case with usb and run 2 systems, only booting one at a time to my Acer Aspire/

 

[AntiZig]

I'm not following what you're trying to do...

You have 2 OS, both on internal HDD...

You wish to buy an external and run one OS at a time.

I don't understand why you need an external.

Yes you can dual boot just fine as long as it's set up properly.

 

[Emerald]

in theory you can as long as you planning on using the BIOS boot device menu.

did the XP drive use to run in this laptop?

if not you might run into some driver and BSOD issues due to the chipset and video drivers.