If xenon... I used this video (just know it's not the best, but it's all I could find) to replace my bulbs... it was really easy once I got in there.
Also, if xenon, replace both at the same time or they will be different colors... not to mention you'll have to do the other one soon anyway.
Alpinweiß 2005 325Ci
Spacegrau 2007 X5 3.0Si