Of course you can have more than one server. You CANNOT have more than one SBS server though. Not sure what the "best" way is... and if the company isn't going to grow much, I'd say you're better off waiting if you can until the next version of SBS later this year (I believe) which will include 2010 and the remote web workplace - which you lose if you leave SBS.
Once you transfer FSMO roles off the SBS server, you will have up to 3 weeks before it starts shutting down periodically.