Dedicated T1 connections

We currently have some users (40) using a Terminal services application called Citrix. They connect to the home office on DSL or T1 lines through the internet could. We get frequent reports of latency in typing and opening files. This never happens on the LAN so I am guessing that is has to do with the internet connection. When I check the bandwidth we are using very little of our total. Some people suggest VPN, some Frame Relay, but I don't know much about Point to point T1 connection. What would you suggest to eliminate latency from our connection?? Who do you suggest as an ISP?? Articles on the web about dedcated point to point connections??