[deadfall]

You are right about the collision course. The two will slowly merge into a bigger galaxy like in this picture: http://cas.sdss.org/dr6/en/proj/basic/galaxies/images/752-6-...

[nacs]

Wikipedia also has a video but this picture also illustrates it well: https://en.wikipedia.org/wiki/Andromeda%E2%80%93Milky_Way_co...