I haven't used the cisco vpn equipment but have used the nortel CES equipment in the past. If the cisco is as scalable as the nortel you shouldn't have expansion issues with either, its just a matter of dollars and preference. In the market now there are more than just cisco and nortel vpn equipment available. Regardless of your preferences...
Determine your application (point to point vpn between locations, main site with remote access destop clients, amount of connections, cost per connection, etc.). Research the available equipment from a number of providers these days and use a matrix to determine which is best to support your app. In short if you have the funds I'd prefer a hardware solution with desktop clients from a known provider than a server based solution - then again i have more experience in hardware than software based vpn's.