Echo the Thunderbird recommendation. Outlook has its points, but unless you need the other features (like diary, address book and the like) to be linked to your e-mail, then it's past its sell-by date.
If you want a more robust filter, spend $30 a year and get a Spamcop account (
www.spamcop.net). I've had mine for many years; it traps about 200 spams a day sent to my "live" addresses. There are a very few false positives (if you have a friend/correspondent who uses one of the more spam-friendly ISPs) and the occasional spam that sneaks through - but 99.x% are accurate.