Question : Best VPN firewalls

I have a corportate HQ and two (more to come) branch offices that I need to tie together.  My main objective is to get the servers talking on the same domain/forest.  If someone has a secure way to accomplish this without a VPN, I would love to hear it.  Otherwise, what is the best firewall/VPN solution?  I've looked at WatchGuard and SonicWall. Thoughts?

Answer : Best VPN firewalls

Personally, I would look at a Cisco ASA or integrated services router for the main office.
For the branch offices it would depend on number of users, but either a smaller ASA or possibly the Linksys RVO42 router.

You are talking 3 sites currently with more to come.  Do you have an idea for how many more?  This will determine the requirements of the main office device.