wsus offline is what I said , and it works on any PC regardless of on domain or not or even connected to the internet (http://www.wsusoffline.net/)
I also do a lot of installs, but being lazy/smart I found creating a single windows 64 bit version that does it all and that has all current updates the easiest way
1. Install waindows 7
2. Insall all updates (roll up + downloaded)
3. Install some basic utils, browser,firefox etc
4. Sysprep system
5. Reboot system
4. Take acronis image of it
Now I can load that image onto a hard drive on a new system in 5 mins
Install chipset, lan, gfx and any other drivers (only annoying part)
Enter windows key then activate, create user account and its ready to go (takes about 30 mins in total)
I had to manage 600+ machine across 2 sites so I had to find the easiest way of doing installs/re-installs