Ok....No probs....
As i said, 1.5.x is the stable version....
I'm running 3 virtual ASSP 2.0.x servers (2 inbound for redundancy/speed, 1 outbound/Spam DB rebuild) and another Spam filter on ISP mail server (Spamborona - it's specifically a Russian Spam filter) - between them, they are blocking around 95% of spam.
If the spam your getting is mainly or all English based - then you should be able to get close to 100% filtering...
You didn't mention which version of Exchange your running.....if it's 2007, then I suggest you look at the SCL options via powershell - you can get the Exchange Transport to automatically move the Spam messages to Junk folders (meaning, Outlook doesn't need to be running to move the message to Junk Folder, Exchange does it) - 'How does that help?' I hear you ask.......Well, your OWA user's will love you for it