Need some advice.

How do y'all control your code when you work on it?
What software do you use to do so?

What I mean by this how do you a) check out code from Production, b) ensure that no one else can check it out, c) move it to a library/folder/que that someone else can move it back to Production

Thanks for any help with this!

Here's a comparison list:
http://en.wikipedia.org/wiki/Comparison_of_revision_control_software

As a user, the two I have had experience with are Subversion (free) and Clearcase (expensive). Both of which will probably do what you want.

If you are a small company, you may be better off writing your own custom system, especially if all you want to do is meet the basic ISO9000 requirements.

My current company uses Subversion. Works very good.

I currently use Perforce (both at work and home) and recommend it highly. Its a robust piece of high quality software that's free for personal use or for OSS development. Commercial licenses can get to be a bit expensive though.

I've also have used Subversion, CVS, and RCS, SCCS way back in the day. Subversion is still viable, but the others are antiquated.

Other systems that I've heard good things about but don't have experience with are Git, Mercurial, and MS's Team Foundation Server.

I would also recommend against writing your own custom system and use one of the free alternatives. If Subversion is fine for the SEI Level 5 facility I worked at, you would have no problem meeting ISO9000 requirements.

I would recommend AGAINST writing your own source control. There are so many good applications out that re-inventing the wheel becomes almost criminal.
I have used perforce and it's one of the more powerful systems, but takes sometime getting used to/configure. If you have MSDN you may be able to get TFS Server which offers its own source control. This is what we currently use and it works almost as good as Perforce, although we do much less source control function at present (little branching, almost no merging, etc...).
Also subversion is a decent one as well.

We use both subversion using tourtoise and git (which is new). I like svn because I'm comfortable. Hate git with a passion but realise its potential and power. Still hate it though. Need a GUI for it (okay, one that's better than the standard git gui or gitK).

We use clearcase at work. find the file, right click and check out to do your work. Otherwise just double click it and it's read-only.

PS, this was the first SimHQ IT occupation topic I have seen that relates to me. That's kinda cool since it's something I would have killed to feel when I was working at my old job.