I ordered 4 new Dells recently, all the same spec, so I set one up with Office, AVG etc then created a ghost image and cloned the other machines quickly... not had any activation problems so far, if you have a valid unused OEM license then you should be alright cos you can just phone the activation line
If you're looking for a free easy ghosting tool then I ended up going with
PING (PartImage Is Not Ghost)It did the trick, and because its essentially a linux live cd, it didn't cost a bean