Good spot about the PCI Express.
I bypassed Vista because I couldn't get a driver for my Delta Dio 2496. When eventually released the interface (Control Panel) is completely different, and less intuitive, but I can confirm the latest one works in Windows 7 Home Premium.
I use Soundforge and v6.0a works well in W7. But I find CD Wave crashes a lot (mouse and keyboard freeze, necessitating a reboot, so make sure everything else is saved and closed down before using CD Wave).