No version of windoze will scale as well as *nix. That *nix can do what z machines do is a (the) reason Larry wants Sun. If you need Oracle horsepower, SQLServer won't do. If you need real MVCC and don't have the $$$, then Postgres is where you'll go. At least in the short term. Whether Snapshot Isolation can be made to behave enough like real MVCC is also an open question. The real issue is the OS. SQLServer has that albatross round its neck.