Just about any pair of jack stands will do. You need to make sure the minimum height is something you can deal with when jacking up the XFire. You have to at least get that high. And make sure the jack stand top pad is large enough to accommodate a rubber-like spacer on it to prevent any scratching of the under carriage. (Note: I've never been a fan of the scissors-type jack stands.)

I also bought a pair of these (Jack Pad Adapters) which exactly fit into the jacking lift pads on the XFire. One of the issues you'll run into is that the ground clearance under the rocker panel of the XFire isn't all that much and adding these adapters, jacking pads, etc., can keep you from getting a lifting jack under the car.