Help with Dual Boot

Hello.
I am considering adding a dual boot to my laptop and am hoping for some step by step instruction.

I want to

• maintain my primary OS on primary drive C
• adopt dual boot
• have second OS reside on USB key or USB external drive.

Normal use I would boot from my primary drive
When booting 2nd OS is desired, I would connect my USB drive and boot..

I haves an Asus G2S running VIsta and I have a little Asus EeePC running Windows7

Hope you can help instruct me.

Dual booting normally refers to two operating systems residing on the hard drive with a menu at start up to select the operating system required. In the scenario you describe the boot from usb or external hard drive is and "alternative" boot source and nothing special is required other than to set you bios to look for bootable devices on usb and to set up the boot image on your usb device. There are many tutorials online for creating bootable usb devices on the web such as this informative page:

Boot From A USB Flash/Pen/Key Drive

thank you.
I'll check it out today.
I did try reading on it... but with no experience with doing it I actually found what I read more conflicting than educating.