According to the specs, the 9500 GT should be the better card. If your motherboard supports PCI Express 2.0, then this card would utilize it. It's DirectX 10, rather than 9, so you're covered there when playing newer games. It supports a higher resolution and is also SLI ready if you decide to buy another one to fill the other PCI slot that won't be hidden under the first card.
All that comes after the fact that the clock speeds and memory is greater on the 9500 GT.