So far I had an APEX guy and a Thompson Creek guy come to my house. The Thompson creek guy's sales tactics were horrible, I couldn't get him to leave. The Apex one was ok in that it was nothing overly pushy. In the case of both, it was just annoying how time consuming the whole thing is.

The Thompson Creek guy did a nice demo showing how heat wasn't getting through the glass so I think his windows may be better than the Apex guy. But I saw somewhere online the whole Thompson Creek pocket window system could be problematic.

I'll check out some of the vendors recommended in this post (Windows on Washington, NOVA Installation, etc).