The US Government's plans to use standardized Windows desktop environments has advantages for non-US Government entitities also. The Federal Desktop Core Configuration (FDCC) specifies reasonable Windows XP and Vista security settings, and application software vendors are encouraged to make sure their products work on a standard spec PC. Tools such as Secutor Prime (free for non-commercial use) will audit a PC against the FDCC and report discrepancies, with enough details for a competent sysadmin to resolve. It's not quite point-n-click one-button-security for the masses but is useful for those who want to improve security of their own Windows systems. Companies that rollout standardized Windows desktops would be well advised to check their standard builds against FDCC too.
I won't go into the downside of encouraging a PC monoculture at this point but leave that for your homework, and Google.