Going to need the model, not just the product line (Latitude is a product line of models..post the model or just the service tag #).
Well, I'd say you have 2 options: 1) try to get it running by setting up an Admin user / removing it from the domain / install drivers OR 2) If you have the product key for the system, wipe the system and install drivers. Product key should be on a sticker on the computer case somewhere.
Option 1) Since it was a domain computer, I'm sure there's an Admin account on the machine - just hidden.
Firstly, try logging in as Admin without a password. After the Ctrl+Alt+Delete screen, you'll need to click "Other User" and then for the username type in ".\Administrator" (without quotes...take note of the .\ before the username). Then try to log in. If it lets you in, great we can proceed. If not, then we'll need to reset the local Admin password.
Option 2) Get the Win7 Pro x64 ISO from here:
[Legal Download: Windows 7 with SP1, 13 languages
Burn it to a disc or use Microsoft's USB tool to make a bootable USB.