software to monitor and push updates/hotfix

I have read discussions here on what the best software is to Push hotfixes and updates on W2K networks, but now cannot seem to find them. What do you feel is the best software application to A: determine what updates and hotfixes each PC on your LAN has and B: push new updates and hotfixes with the least effort? (with weaknesses and strong points for each) Your thoughts and opinions are highly regarded!

Thanks!