I think that, although processor speed is very much needed, Flight Simulator 2004 gets more performance out of a good graphics card and RAM. Much of the special things that makes Flight Sim a great looking game, are actually performed by the graphics card, not the CPU. I have proven that by running FS9 in different machines with different cards and processor speeds... and to be honest, Graphic Card and RAM its what set the difference, not processor speed, althought it is indeed, very important. So, to me, his 1.8Ghz would work only if he upgrades RAM to, say, 768MB or 1GB. The more the better. Also, a good graphics card. This latest nVidia GeForce 6600GT is an awesome card. Based on these specs, I don't think PCIe is an option for a Radeon X series card.
Effects that are now performed by the video card:
- Pixel shaders, water reflections
- MIP Mapping
These are things that basically, makes the whole simulator. The processor has really not much to do there.
To answer your question: Nope. Its not good. It will run flight sim, but not very good. Would you at least tell what's the Graphics chip??