I just downloaded and installed the newest Vista driver on the Windows 7 installation and it is working just fine, in fact I have better volume and EAX seems to work as well.
The driver file is SBAX_PCDRV_LB_2_18_0010.exe and appears to have been posted within the last couple of weeks over at Creative.
The last word I saw posted from Creative about an Audigy 2 ZS driver is that it would be considered but no date is available yet. In the meantime I'm going to keep on trying to use the Vista driver.
No, I did not have to use compatibility mode to install it. The installation removes the Windows 7 Update driver and goes through it's paces with no problems.
I do have Windows 7 build 7068 and the noise seemed more prevalent in a previous build I had been trying (7057).
Hope this helps someone else...