Just Flight adds two products at simMarket store :

• The 737-100 FSX pack of Just Flight comes as an expansion for 737 Professional, that is required and not included. The base pack can be found here. With 737-100 model, you get 10 airlines liveries included.
• Designed by Aeroplane Heaven team, the P-38 Lightning can be used either with FSX or FS2004. Try the working guns and cannons by the way.