Personally, I would. It depends entirely on the situation you're in; how long you've been together, why they cheated, if they've done it before, the boundaries of your relationship, etc. I just got engaged and have absolutely no fear of him ever cheating on me but even if he did I would take him back. It's just the way I am. We've been together for so long and shared so many things with each other it would hurt me more to say goodbye than to accept that he cheated. Plus from the way I see it if he cheated on me, because of the way our relationship is, I would see it as my fault because I wasn't good enough (not saying this would apply in any other relationship). Of course it would hurt me and I would be angry and upset but I would still love him, and after time I would forgive him no doubt.
I try to tell this to as many people as I can when dealing with relationships but time really does matter sometimes, especially in the way you handle situations like this.
A relationship generally has three stages; the honeymoon phase, the tough it out phase, and the cruise phase. Once your in the cruise phase you've pretty much got a steady relationship. In the other two however its hard to say that you really know the person completely. Them cheating on you could be part of their character you've just never seen before.
If they've cheated on you before and you got over it you probably need to start to watch your back. Once is enough to know that it's wrong.
And of course the boundaries of your relationship need to be taken into consideration as well. Cheating in an open relationship isn't even close to cheating on your one and only.
Just my feelings on the subject :)