Question : Problem: Office to Office VPN's with different brands of firewalls.

This is a general inquiry about VPN interoperability between different brands of firewalls.  Can IPSec VPN's be setup between different brands of firewalls fairly easily or is an up-hill battle.   I know that configuring VPN's between matching firewalls is easy because I have done it a few times.

We have a couple of remote offices that have different firewalls and we want to set up VPN's to our office.  If we get a Watchguard or Sonic Wall product or similar product, will we have a problem.

Any recommendations are welcome.

Answer : Problem: Office to Office VPN's with different brands of firewalls.

That is correct.  If both firewalls support IPSEC for the tunneling protocol, then you should be able to find matching IKE and IPSEC parameters so that they can negotiate and establish a VPN tunnel session.