I tried running Windows 7 on a machine that had a Creative Sound Blaster Live 5.1 card inside. Since the 5.1 is a decent card I see no reason to replace it just because windows 7 came along. Please note that these unofficial updated drivers also bring along Windows 64 bit support. A quick google search revealed this:
Please note that this is an unofficial patch and that it has problems if your Windows 7 machine has more than 2 Gb of RAM. Read all the details and download the package over to the above address. Let me know if it goes offline, I can upload them too somewhere.