What’s the most popular PC SCSI card of all time? 1541C? Maybe. Or it may be the AHA-2940 family. It’s up there, anyhow. And what card did Microsoft (and Adaptec) drop support for in Windows 7? The AHA-2940. Fortunately, I found a workaround which appears to succeed:
http://social.technet.microsoft.com/Forums/en/winserverfiles/thread/bf0bb207-3b5d-489d-be74-56031dfe4651