[JMS40]

Just for clarity... There is no Vista WAVE driver but there IS a Vista ASIO driver.
And, yes it is single client (only one program at a time) but you are not confined to one stereo out. The ASIO driver can utilize all the multiple I/O's of your Digi device.

Dwags1... the ASIO driver should have been installed along with 7.4. To make sure, go to Add or Remove Programs and choose to Modify your Pro Tools installation. Make sure ASIO is checked off as an option... don't Un-check any of the other options or they will be un-installed.

Once you are sure the ASIO driver is installed, it should be available inside the audio preferences of any ASIO compliant program.

Good luck-