hi there, the front panel of the audigy will fit into the case no problems...
the graphics cards are a mine field ..... have a look round online - the 8800gt is the newest card out and probably the best selling at the moment.....buit the gtx is the more powerful one.....
either card is going to make your old 7600gt look like it from the dark ages....
you can look at this post -
HERE
have a couple of comparsion for differnet graphics card i found on hexus....
hope this helps
mark