I am flying XAR on my laptop and have not had any problems since downloading the patches.
I had some minor problems until I downloaded the patches.
Make sure you have the latest version (downloadable at the XAR website). The latest patch is a 30+ meg download so I hope you have DSL or a lot of time on your hands.
What are the particulars for your computer...you may need to get the newest drivers for your video and sound cards too.
I am running a Gateway Laptop with P3 1.06gig on Win XP home with 382 Meg RAM on board. Video is a NVidia GeForce Go with 32 meg Ram,