Highfly3d,

AFP has a lower system requirement compared to AFPD.

The recommended system requirement for AFP is:
- Intel Pentium II compatible processor with at least 700 MHz or
- AMD Athlon compatible processor with at least 700 MHz
- OpenGL compatible graphic card with at least 32 MB
- 128 MB RAM

Compare this with the recommended system requirement for AFPD:
- Pentium 4 with 2.0 Ghz or
- AMD 64 with 1.6 Ghz
- 256 MB RAM
- OpenGL compatible 3D-graphics card with 128 MB (256MB are only required if using AeroFly with full antialiasing and very high monitor resolutions)

The 5700 will work with both AFP and AFPD

Here's a non-exhaustive comparison between AFPD and AFP:

Models:
- Flight physics improved.
- Higly detailed new models, which are not available for AFP
- Light weight aircrafts (foamies like shockflyer) and helicopters (piccolo) now work correctly.
- Left turning rotor systems for helicopters added.
- More than 4 rotorblades supported.
- Dual head helicopters supported.
- Smoke now supported for 2 models.
- Model surface reflections can be switched on/off.
- Glider sound added.
- 4D models with PPS (push-pull-propeller-system or VPP).

Sceneries:
- Besides the 3D sceneries, a new panorama (photorealistic) scenery function has been added

Sound:
- Background music can be switched on/off.
- mpeg music clips can be loaded.

Handling:
- Large preview image and preview text added to model selection menu.
- Help text added to main menu.
- USB cable instead of serial cable.
- Improved interface for easy/advanced transmitter setup.
- High quality screenshots and video can be saved, number not limited.

Free downloads:
- All the newer free models and sceneries are only developed for AFPD.

Hope this helps.