VPN and Internet simultaneously

Hello
I have a client that has one main office and two branch offices, all of them have Windows 2000 Server installed. At this moment there is only one connection via ISDN to one of the branch offices. Right now this client has
1 512mb DSL connection, and he need?s to be able to have 2 VPN connections and Internet access simultaneously. I know that I?ll need to upgrade the DSL to 2Mbps. I have looked at two possibilities a Firewall/VPN router like the new (USR808200) or ISA Server2004. What is my best choice????