VPN setup suggestions needed

[mikesg]

I am working for a small non-profit that is moving from one facility to three. They will be located within a block of each other and will all use the same ISP with 40Mb/10Mb FiOS connections each and static IP's. I currently have an OpenBSD 4.3 gateway/firewall in place (lets call this home) and plan on using two WRT54GL routers running the DD-WRT VPN firmware at the remote sites. The thought was that I could run OpenVPN in bridged mode (tap) connecting the two very inexpensive Linksys routers to the existing firewall. This would create a simple extension of the home network to the remote locations, if my understanding is correct.

I have the two routers flashed with DD-WRT and OpenVPN 2.1 RC19 (from source) installed on the firewall. This is a small office running XP and Vista on a Windows 2008 AD domain totaling less than 20 computers with one remote site having two computers and the other five or so. I'm in need of some OpenVPN/OpenBSD help here, but before I lose hours of my life going in the wrong direction I would like to ask if this seems like the best approach?