No, it seems that the user of that install has installed winrar himself. It's very unlikely that MS is going to include winrar by default.
It may be a stupid question, but where on the server is it? I can't find anything on BA ftp. EDIT: Sorry found it! Wasn't put in the beta os folder So it's final M1 build?
Anyone fancy PM'ing me their logon for beta archive, I can't download without being an advanced user, thanks