Connectivity Suggestion

I would like other's opinion on this.
My quick scenerio:
1 Corporate office, small Lan 16-user.
16 restaurants with only 2 PC's in each one.
These PCs typically use a Terminal Services Server and Exchange (Internal office email only, no SMTP).

Any suggestions on connecting every restaurant location to the corporate. As of right now, they're using DSL or cable w/static IP and VPN Linksys routers. But, I have to question this since there's so much time devoted to them troubleshooting the connection.