It's hard to say without your service tag to know what motherboard they installed, what type of ram you're using, etc.
You can access a lot of automated info by entering the service tag at Dell's site, available by clicking here
But you're going to be limited, at best, expecially by today's standards.
You might be better off getting a new system and installing your hard drive as a slave, if you're attached to some of what's installed there. You'd still have to have access to installation files for all your applications, though.