I'm wanting to put Windows 7 on a external harddrive so I can use it to run a PC if need be can anyone tell me how this is dine and what software I will need,and what steps must be taken to pull this off.
Best option for booting to an external is to boot to a live cd of Ubuntu or Mint. There are projects that are trying to do what you are asking but you can boot to a linux cd or better yet a large thumb drive and have access to apps and browsers and the driver support is very good.
You do it like normal.. during installation.. it will ask where you want to install .. just select the external HD .. Now from what you wrote.. you're insinuating that you want to be able to move this External HD around to different PCs ? This will not work because the OS is Hardware Specific . .
Depends on what you mean you can do this by taking one and hooking it up to a USB port or flipping the drive out manually and inserting a different one... My best guess is that you won't need any software at all it should be in your Bios under the boot priority... I would recommend that you use Linux or a variant of it with a live cd if you wanna play around with the OS you have installed its much easier... Also if you want to move this OS to a different machine like Iamanoob said it won't work unfortunately...However if it makes you feel smarter it works with Linux lol...