I have Realflight G2 running on a Dell Inspiron 2 Ghz laptop with Windows 2000 Pro. No problems, but you do need to download the latest updates from the Realflight website.

If there is no gameport on your laptop and you are using the non-USB Realflight, you need to get a gameport to USB adaptor. They are $15 at Radio Shack, or anywhere from $15 - $25 at other electronic parts stores and on-line. I bought two adaptors from the local Radio Shack in north Baltimore two weeks ago, so they are available. Two other Radio Shacks in the area were out of stock, so you may need to search.

I have used the RealFlight controller box with FMS, both directly through a gameport and through the gameport->USB adaptor. So that combo works too.

I have also used RC radios (Futaba and JR) with trainer port adaptors both with FMS and RealFlight. The trainer port adapter reads the PWM signal coming from the trainer port, and converts it to the expected gameport inputs (0-100k Ohm) with four digital potentiometers. These kinds of adaptors are available all over the net:

The first one is a kit - I have built two and they work great:
http://www.welwyn.demon.co.uk/joystick/joystick.htm

The second is pre-built and I have one of these also; it works great:
http://www.rctrainer.com/

I have not used this kind but it appears to be similar to #2 above:
http://www.ripmax.com/ProductFrames/P-SIM100.html

Chris