>The clients need to have a kind of sql server on there local computer
>
>Is there a single user version available

This is a perfect scenario to use MSDE. Here's some information that may help.

A backgrounder on SQL Server replication
http://msdn.microsoft.com/library/backgrnd/html/msdn_sqlrep.htm

A backgrounder on MSDE
http://msdn.microsoft.com/library/backgrnd/html/msdeforvs.htm

-Mike