VPN ideas for a very small office linked to a small-medium sized office.

 I work in IT at a manufacturing company, and we have a corporate office which is located several miles from our manufacturing plant.  Both locations have offices, though the plant only has 3 computers.  The corporate office has 10-15 computers.  This is the current setup:

Corporate Office:
Windows 2000 Domain, domain name Corporate.ClarionBathware.Local
Uplink is a frac T1 (8 pairs)
All domain clients running Windows xp, with the exception of one linux box used as an IDS.

[ALL OFFICE COMPUTERS] <--> [SWITCH] <----> [HUB]  <--> [LINKSYS CABLE/DSL ROUTER] <--> [T1]
                                                      |                  /    \
                                      [DOMAIN SERVER]  [IDS]    [WIRELESS ACCESS POINT]
Manufacturing:
Windows 2000 Domain, domain name Corporate.ClarionBathware.Local (same domain name, so that laptop users could traverse between facilities and make moving between domain servers seem transparent)
Uplink is a dialup 56k modem, moving towards a speedier wifi solution, no other cost effective internet service in the area.
All domain clients running Windows xp.

[ALL OFFICE COMPUTERS] <--> [SWITCH] <--->[LINKSYS WIRELESS CABLE/DSL ROUTER]
                                                      |                                       |
                                       [DOMAIN SERVER]             [Linux box serving as dial-up router (freesco)]
                                                               

Neither of the linksys routers are models offering SoHo VPN capabilities, and we are aggressively seeking a cost-effective VPN solution.  The VPN Solution would have to envolve file/printer sharing between the two offices, and hopefully would allow
for creating ODBC (TCP) connections as well.  My personal knowledge lends more to programming than it does towards network design, and I was hoping somebody would be willing to post various ways to implement a VPN, as well as the approximated costs envolved in each method.  Thank you.