Well if you are looking for a desktop, look for a monitor that is flat-screen. If you are looking for a laptop, make sure that its memory is at least at 2GB and make sure the processor is at least 1.8GHz. The more memory, the better, but I wouldn't go any lower than those numbers.
Edit: Either way, if you are looking for a desktop or a laptop, you want to make sure it has a flat-screen monitor AND at least 2GB of memory and at least a 1.8GHz processor. Like I said, the more memory, the better.
Sorry if I made it a little confusing.