I have the same issue, since I built my case for a Vibra 128 and now I wanna upgrade to a better card and both the Audigy and Live cards are alot higher.....
I am looking at the Philips Seismic Edge sound card......
http://www.digit-life.com/articles/philipsedge/
lower height, and without the firewire option as with the Audigy, which is a bit lost in a car setup IMHO...