Will installing Vista reformat my HDD?

I'm thinking of installing Vista on the external HDD of my XP PC to play directx 10 games, but not use it as my primary operating system. Is it safe to install it on my external HDD (which has no operating system, but I use to install games and itunes music) without erasing the contents of the drive, and will it have any other negative effects?

Welcome
If there is no OS on the drive now, you must do a clean install and everything on the drive will be lost.
http://www.vistax64.com/tutorials/117366-clean-install-full-version-vista.html
The drive will be formatted.

richc46 said:

Welcome
If there is no OS on the drive now, you must do a clean install and everything on the drive will be lost.
http://www.vistax64.com/tutorials/117366-clean-install-full-version-vista.html
The drive will be formatted.

Click to expand...

Hmm, if that's the case I won't really be able to do it since i don't have enough space to back up the data. Would it not be possible to create a partition on my secondary internal HDD and install it to that without effecting the rest of the drive?

Note that Microsoft has never supported installing an OS to an external drive. The only exception being Windows 8, Enterprise Edition. This is not a retail product but only available to a large organization through bulk licensing. While it may be possible to install the OS it isn't very practical.

LMiller7 said:

Note that Microsoft has never supported installing an OS to an external drive. The only exception being Windows 8, Enterprise Edition. This is not a retail product but only available to a large organization through bulk licensing. While it may be possible to install the OS it isn't very practical.

Click to expand...

The external drive thing isn't really the issue. I have a second internal hard drive too which I only use for storage and could be used to install Vista. I'm just wondering if it's possible to install it, creating a partition or something if necessary, without erasing the contents of the HDD. Vista is my only real choice of OS because I have a spare copy of it that came with my pc before I downgraded to XP (I have too much stuff that won't run on a newer OS to upgrade.)