Cisco VPN Client for 10.5.3

Cisco VPN Client 4.9.01.0100 works for 10.4 and later, including 10.5.

It can be hard to find Cisco VPN client downloads, Andrew got this one for me.

Update: I couldn't get the image to download fully, and now it's offline. Comments tell us Cisco's distribution policy has not change, this was an unauthorized image and it's probably been removed.
I was able to download an image through my university account. It took 3 tries, I kept finding older versions on various U servers. The official site (UMN authentication required) had the version I needed: Cisco VPN Client 4.9.01.0100

I think for most people that's the best way to get an updated VPN Client -- find someone with access to an university account and ask them to get the client. Just be sure they know what the latest version is! I suspect many universities have multiple distribution sites.