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Not sure which types of collision detection would be most useful to you. If you're doing 2d tile platformer these might help:
Types of tile based collision methods:
http://higherorderfun.com/blog/2012/05/20/the-guide-to-implementing-2d-platformers/
Pixel perfect collision detection:
http://gamedev.stackexchange.com/questions/15191/is-there-a-good-way-to-get-pixel-perfect-collision-detection-in-xna
Here you can find rectangle-based collision detection source code - also links to pixel-collision and others:
http://xbox.create.msdn.com/en-US/education/catalog/tutorial/collision_2d_rectangle
I'm thinking rectangle-rectangle collision detection works for most things (but may want to try bounding-circle [radius-overlap] for some things)