I am currently using the top of the range creative card (the xfi elite pro) and its very nice. Other cards I would reccomend are the Auzentech prelude, Asus Xonar and definately the razer.
As greenmonkey mentioned the EAX with vista is a problem as not all games are compatable with the Alchemy converter so the benefit of xfi cards being able to support EAX5 is pretty much void
(the reason for this is that in vista microsoft removed the possibility of hardware acceleration for sound. This means that they changed the driver model of the operationg system and no driver fix etc is ever going to sort that out.)
Reports from the Asus Xonar card are great and Asus are reportedly developing a system that will natitivly translate all EAX sounds over to Vista complatability effectivly giving you full EAX support. Im not too sure how this is going to work or when it is going to be fully implemented etc because i jsut read a brief article on it (in other words google it and dont ask questions

)
So my best advice is workout what you REALLY need from your sound card in terms of connections (stereo, 5.1, 7.1, optica, coaxial, aux inputs etc) If you dont need a card with a breakout box dont spend the extra money on it.
Then work out what OS you are going to be using and if you are going to be wanting EAX support.