Even though VPN is the wave of the future at this point you should only be considering this medium of you meet the following criteria.
Data not critical. Just try getting an SLA out of your ISP. The only thing they will give you is link uptime. If you need packet prioritization, forget about it. Also Video is definately out. VPN is great for remote office access and telecommuting. I just installed a redundant Nortel VPN service for telecommuting. It works great. Just make sure that you have management access to the system for creating,deleting users and adding groups and filters.
Good Luck