We use a failover firewall (2 SonicWalls), ISA server, proxies and Symantec messagelabs and antivirus for realtime protection. Encryption is fun, but is sometimes tougher to manage than to prevent data loss.
Personally i use TrueCrypt, but not on corporate level.
In a few months we will be using Server 2008’s DFS with three data centers. SCOM will also be implemented, which will give us tools to prevent a lot of bad things from happening.