Where to install steam to and is Cnet right it will nuke a HD?

[BOBC]

Hi,
I read in the ubisoft forum a post by Tully that says :-

I would suggest you put it somewhere other than C:\Program Files or C:\Program Files (x86) incase you wish to run older games from Steam.

I have never used Steam before and want to be sure that Cliffs of Dover runs correctly and also with the Team Fusion patches.

Can one install Steam to any folder on any drive on a PC and why is he suggesting this , surely steam should be designed to have the install allow one to play older games from them ?

I also see a Cnet article
http://www.cnet.com/how-to/how-to-in...your-computer/
that says to install SteamOS one needs an empty usb HD as steam will nuke a normal one...what ???

I have purchased CloD jan 2013 nd have an count name and confirmation code. I see I need to go to steam game library to install it. I trust it will ask me where the steam folder is, or do I install it elsewhere to steam ?

BOBC