congrats on the purchase. I bought a '08 last winter for my wife and so far we really like it minus a few electrical glemins as mentioned (cd player stops working). I thought I would post regarding the staggered setup question. I bought 19" staggered rims for the x3 at the beginning of the summer and have loved them so far. Here is the post I made with some pics and sizing.
http://x3.xbimmers.com/forums/showthread.php?t=672294