Exchange anti-spam

[nanaki333]

Just as the topic says. I need some help finding a good anti-spam program that involves the least configuration as possible as well as it being cheap. Needs to work with exchange2000. I've been running symantec, but every time the list gets really big, it starts deleting a whole bunch of legit e-mails. Can anybody think of any good software I should use? I was looking at ihatespam, but I want to keep my options open. Preferably something with a trial so I can test it out before I blow $500+ on it.