Upgrading dimension 4700 video to 9500gt

I'm upgrading my wife's Dimension 4700 video card to a 9500gt.  The problem I have is space.  I found that the card is wider than the space between it and the audio card, so installation without some moving around is impossible. 

I plan to remove the 56K modem from the third slot and move the audio card to that (third) position to make enough room for the 9500gt.  the question is what problems will I create with address issues etc. for the sound, and how do I prevent/correct them?