I just installed the Windows Mobile 6 sdk, can I use it to develop software for pocket pc 5 devices, or should I also install the Mobile 5 sdk ? thanks.
In case you don't really care if it's going to work on WM 5.0 correctly, you’re good to go with WM 6.0 SDK. Otherwise you should install SDK for specific platform you're developing for and test on it.
You could applications that do not use any WM 6 specific features/APIs and deploy them on WM5. However, in order to deploy the application from VS (and debug) on a WM5 device - I strongly recommend you have installed WM 5 SDK.