corporate network protection against spyware

Hi, I am part of an IT department (Alliance Atlantis Communications).  We are running a 2000/XP environment (servers and clients).  Currently most users have administrative rights to their PCs, and filtered access to the internet through websense (blocking only sites with certain content flags, such as dating/personals, adult, etc.)  HOWEVER, since users have administrative rights to their workstations and surf the web like mofos, I've been finding between 2-300 spyware/adware/crap instances on each PC on average when troubleshooting weird stuff like homepages changing, IE crashing, IE bars appearing, etc.

I know there's a spyware plugin for websense that provides network level protection against spyware, but before spending $11,000 on that plugin I was wondering if anyone else knew of an alternative.  It has to protect the whole network, be supportable (ie not freeware) and work decently well.

I believe Adaware Professional has network level spyware protection, anyone used this in a corporate environment?

Appreciate your feedback.

have a look here you may find something>http://www.webroot.com/wb/downloads/index.php

Many thanks for your feedback.