ISA 2006 hands on Labs VHD downloads available from Microsoft, you can download the vhd and test the following functionalities of ISA 2006:
Module A: Introduction to ISA Server
Module B: Configuring Outbound Internet Access
Module C: Publishing Web Servers and Other Servers
Module D: Publishing an Exchange Server
Module E: Enabling VPN Connections
Module F: ISA Server 2006 as Branch Office Gateway
Module G: Enterprise Management of ISA Servers
Module H: Configuring Load Balancing
Module I: Using Monitoring, Alerting and Logging.
Click here to download the vhd