Probably a little late for your chili cravings but still an interesting topic.
The answer to your question is BOTH.
In a 1 cup serving of kidney beans you will get ~40grams of Carbs and 15 grams of protein giving you a near 4:1 ratio on carbs to protein. If you take into account the level of fiber and other nutrients I would say EAT THEM.
The only time you should avoid them is on a low-carb diet which I don't suggest for P90X (fatigue will hit you, trust me i tried).
Here is a good url to help you see all there is to know about kidney bean nutrtion:
http://www.whfoods.com/genpage.php?tname=nutrientprofile&dbid=49