I have replaced all of my window regulators myself. Actually it was alot easier then I thought it would be. The hardest part is getting off the noise barrier on the inside of the door. Its like a sticky tar that hold it on and it tears easily. BMW recommends replacing it but i just stuck it back on, thats up to you i guess. But after that, just a few bolts and some tricky manuevering and the old one came out and the new one went in. Took me a couple hours and I was done with all 4. Good luck!
<img src='http://www.bmw-forums.com/forum/index.php?act=Attach&type=post&id=18826.jp g' border='0' alt='user posted image' />