Dishonored vs XCOM, I can only afford one!

Two games that are getting great review scores. Both seem right up my alley as far as gameplay and aesthetics. Only one will be purchased by me this week!

Money is tight right now for a collage student such as myself. As it happens I can only fit one of these games into my budget right now, the other will have to wait a little while. I love what I'm seeing about both of them, and based on similar games I'd say I'm comfortable with both genres.

As it stands XCOM has a slight lead due to its multiplayer options which seem to give it more longevity. At the same time Dishonored has a plethora of choices which could definitely extend the gameplay time through multiple play throughs.

Second question is what platform to get it on, PC or 360. Overall I'd say I'm a PC guy, but I could be convinced otherwise.