With the 19's I'd say 12mm.. up front and 25mm or 30mm in the rear (it's a 5mm difference). H&R is the way to go.
http://www.turnermotorsport.com/BMW-...l-spacers.aspx Here is where to buy, they are great people.
make sure you pick the right ones the fitment is listed in the description, all x5's are the same except for the x5m.