Yes, you need Steam for CS 1.6, and no, it won't do anything to NS. Just don't check the box that tells it to remove the old HL installation and you'll be fine (and NS 3.0 is Steam-only anyway).
<a href='http://www.unknownworlds.com/forums/index.php?act=ST&f=31&t=49430' target='_blank'>The 2.0 beta NS steam client can be found here.</a>
<a href='http://www.unknownworlds.com/forums/index.php?act=ST&f=18&t=47676' target='_blank'>Common fixes to get it working like smoothly can be found here.</a>
<a href='http://www.steampowered.com' target='_blank'>Here's the official Steam site, from where you can snag all the steam files that you'll need.</a>
Basically, those two threads and steam are all that you need to get it all set up. Just follow the instructions as explicitly as possible, and you should be fine. Good luck <!--emo&:)--><img src='http://www.unknownworlds.com/forums/html/emoticons/smile.gif' border='0' style='vertical-align:middle' alt='smile.gif'><!--endemo-->
Comments
<a href='http://www.unknownworlds.com/forums/index.php?act=ST&f=18&t=47676' target='_blank'>Common fixes to get it working like smoothly can be found here.</a>
<a href='http://www.steampowered.com' target='_blank'>Here's the official Steam site, from where you can snag all the steam files that you'll need.</a>
Basically, those two threads and steam are all that you need to get it all set up. Just follow the instructions as explicitly as possible, and you should be fine. Good luck <!--emo&:)--><img src='http://www.unknownworlds.com/forums/html/emoticons/smile.gif' border='0' style='vertical-align:middle' alt='smile.gif'><!--endemo-->