Forwarded by Siderea: How to win at Monopoly and lose all your friends:

Your goal is to play conservatively, lock up more resources, and let the other players lose by attrition. If you want to see these people again, I recommend not gloating, but simply state that you're playing to win, and that it wasn't your idea to play Monopoly in the first place.

Do some research on BoardGameGeek.com, and head down to your local gaming shop, where more often than not, you'll find knowledgeable staff and even demo sets for you to try before you buy. It shouldn't be too hard to convince your friends to try something new, especially if you offer to play another round of Monopoly.