How much wattage do I need to support a XFX GeoForce 9500e 1g graphics card and MS Flight Simulator?

I can't answer the question about the graphics card. I googled it, but I don't find any information on it. Graphics cards can use a bit of current, but they're not that current intensive.

MS Flight Simulator is a program, so running that program won't require more power than running a full suite of other programs. The CPU's and the GPU's power requirements are what you need to pay attention to. Of course, the GPU is on your graphics card.

If you're not overclocking or doing anything very radical, you should be able to get by with a 300 watt power supply, easily. If you have a lot of add-in cards, hard drives, USB attachments, a 400-450 watt power supply might be needed.

Extra large power supplies aren't expensive and you can usually get them in the same sizes. Also, using a 450 watt power supply when you're only drawing 200 watts doesn't really hurt anything. But I have a hunch you already know that.