I've setup a VPN for a remote user to login to our company Quickbooks file to work as if he were here in our office. The remote connects quickly to the server, but as soon as he goes to open up a file the connection becomes extremely slow. We are both running 200+ rate DSL lines. Any suggestions?

Server is NT4 on a 750Mhz system; remote system is WIN2000 on a 900Mhz system
Both have 256Mbs Ram