Alternator Replacement

[quizzyjones]

My battery light came on on the way home from work yesterday. The battery is only three months old. I took it over to my local BMW dealer and they took a look at it and have determined it to be the alternator. For only $665 plus two hours of labor they'll fix it.
I almost fell over right there in the dealership. Apparantly our alternators are "water cooled" and therefore cost $953.45 to be replaced. I dug around on the internet last night and found the original equipment Bosch alternator for $350.
I went ahead and orderd it. I was wondering if anyone here has had to do thier alternator and how easy was it to get to, better from top or bottom and so on. Also being "watercooled" is there any thing else I should know before trying to tackle this myself. Thanks for any advice.

2001 X5 4.4i
Sport Package