You don't say whether this is a Laptop or a desktop (Mini Tower). Now from my own research on the product I'm going to make the assumption that it is the Desktop version. This means that you are in luck. I would suggest that you go for the Nvidia GTX 460 (1GB) as a minimum for keeping your computer future proof. I would also suggest you upgrade the power supply to at least 800W, as this particular card is a power hungry beast and will blow anything up to 650W.
I beleive the Studio series do not have interchangeable video cards. That thing is built into the motherboard. You can't just change it. It isn't a desktop...