One more thing to consider is what does SSO mean? In my workplace we have SSO but it is not integrated with the windows password. Technically, I have 2 logon twice. Once to XP and once to the SSO client. The SSO client then proides access to all backend systems of which there are many. Note I am not bothered by this but at another shop I worked at the CIO at the time wanted what she called true SSO (the client must be integrated into the windows logon). You should find out if that is required.
Cheers,
D