I just moved from a SB Live! to an X-Fi Extreme Music and I am on the virge of reformatting. I uninstalled the old card, drivers, and applications just like anyone else would. I installed the X-Fi and its associated software and whaddya know...it still was looking for the old Live! card. I guess I should have gone in the registry to make some changes, but not being a registry guru, I didn't...besides the fact that it wouldn't be necessary.
As a result, my MediaSource and certain consoles don't work. I recommend a reformat, if only for peace of mind.