Depending upon how many concurrent users, I'd use Terminal Services. Either
Windows, WinConnect, or if you like to spend money, Citrix.
Your speeds will be roughly comparable through the VPN to what they would be
on a LAN. The FE are kept in separate folders, 1 for each user, at the main
network server.
Merely converting to SQL-Server will give you a little to none performance
gain unless you rewrite the application to use totally unbound forms and
very small datasets. For your situation, there are 2 solutions, rewrite the
FE as an asp application, or Terminal Services. A SQL-Server back end allows
more users, 24/7 operation, and some more security, although a VPN is
probably the main element in security.
The cheapest and easiest solution is Terminal Services if your situation
permits it.
BTW, it is way too easy top drop packets or corrupt a database using bound
forms over an Internet connection. I'd make your decisions quickly.
--
Arvin Meyer, MCP, MVP
http://www.datastrat.com
http://www.mvps.org/access
http://www.accessmvp.com