If you haven't done it, disable the Integrated (on the motherboard) audio in the BIOS first. Two audio devices can conflict and cause problems.
The Multimedia Audio Controller is part of the sound device/drivers
. When you get the SoundBlaster properly installed that should go away.
On the other hand, the old (and that is an old sound card) card may not work on your Win 7 system or may be defective. Actually, if you have a relatively new PC (or motherboard) the integrated sound on the motherboard is as good or may even be better than the old Audigy 2 sound card.