For working remotely I've been using the Cisco VPN Client on OSX for about 3 years. What recollections I have about the installation procedure is that the installation file for OSX is extremely hard to find on the Cisco web site. After registering as a user and then clicking on a series of navigation trees and links and download buttons, sometimes you still had no luck, and if I had to do it all over again, I probably still would have a hard time just finding the file.
Recently, I had to help someone else set this up on Snow Leopard, and to my chagrin, failed to locate that file on the Cisco web site - who knows, maybe they've removed it completely: their Mac version already seem far behind 3 years ago. Then I tried copying over the CiscoVPN application - that did not work. It was an overall failure. But, I had a second crack at this when I got a new laptop myself. I am the first in my family to have the Lion OS, so I decided to have a go at Google adding "lion" in the search term, i.e. "cisco vpn osx lion". It turned up this StackExchange postwhich turned up a solution that's ten times better then Cisco's crappy website and software.
The SE answer is great, but I'll repeat it here nonetheless because I am so outraged this isn't more widely known and there are still unsuspecting folks out there trying to go through the hideous trap that is the crappy Cisco web site.
As it turns out, you don't even have to install anything. OSX has a Cisco-compatible VPN protocol built-in. Here's how you set it up.
Step 1
Make sure you have the VPN connection info, you should have gotten this from your IT department. This should include a server IP address, a group name and a secret. Also make sure you have your user name and password - this should be the normal login you use day-to-day at the office.
Step 2
Go to System Preferences, click on Network.
Step 3
Click on the + button on the bottom left to add a network. In the popup: select VPN for Interface, and then Cisco IPSec for VPN Type. Choose a memorable name for yourself for Service Name. Click Create.
Step 4
Type in your Server Address, Account name (user name) and Password. Then click on Authentication Settings... and fill out Group name and Shared Secret. Click OK.
Step 5
Click on Connect to test the connection. I also like to check Show VPN status in menu bar,
that way I can always see the status and be able to connect and disconnect from right there.
Did That Work For You?
If you are running into this problem, I hope this procedure did the trick for you. If not, check the SE answer for more clues, or leave a comment, and maybe I can help.