Slow VPN connection from W98 clients…

I have an NT server that uses PPTP to listen for incoming requests for a VPN connection from W98 clients who connect through a dialup internet connection. The server is connected using a broadband link. On the W98 end, file transfers seem slow andjust the other day while looking through event viewer, I saw that is was logging the connection and saying that they only connect at 9600. How do I increase this connect rate? Is there a setting someplace? The W98 client connect to the internet in the 50000 range. The server provides http and ftp at broadband rates so upload speed is not limited…help!