E-MU and Creative drivers are done by separate groups and have very little in common.
Where Creative's drivers are often considered a POS, EMU drivers are one of the things E-MU's pride relies on.
There is just no comparison between the two.
I have both Creative X-Fi drivers and EMU 0404 USB drivers installed and neither causes issues for me on Vista64. X-Fi drivers are a lot more complex than EMU drivers because they are meant for 3D sound in games so one would expect those drivers to have more issues but they don't for me.