I have lots of questions regarding VPN. We have a Vb6 applications made for a school. We have developed admissions, grading, accounting and class management modules running on windows XP machines. We use SQL server 2005 for our database running on windows 2003 server configured as a domain controller for the entire system. Our school is branching out and one of the requirements is to connect remote clients to our SQL Server. The only way i can see this is to use VPN in which i don't know anything about. This will be the first time we are going to use this kind of technology.

These are my questions.
1. Are VPN connections fast?
2. Do i really need three servers to set up a VPN? (1 domain cotroller, 1 VPN server, 1 authentication server)
3. Are there other solutions?
4. do I need to subscribe to a commercial telco for VPN?
5. Can I use a 2 mbps DSL to DSL line for VPN?

Any comments is highly appreciated. thanks