For future reference, asking for advice after you've already made the decision and spent the money isn't very useful. What would you do if we came back and said the card wouldn't even work in your system?
That said, the GT 430 will be a solid upgrade, but not a huge one. I wouldn't expect to quadruple your framerate, or anything like that. You basically just replaced a 5 generation old mid range card with a 3 generation old bottom of the line card.