Invoke a scanner/video camera using VB.NET

Hi !! My application is in VB.NET and it requires me to do the following things : 1) Invoke a scanning device and scan images. The idea is to just invoke the native software application used for scanning and display it to the user giving him the feel that it is "my" application which is doing the stuff. 2) Similarly I would like to invoke a web cam and a video camera plugged on to the computer. 3) With a video camera, I would like to freeze an image at any particular point and save it on to the hard disk. This could be the native feature provided by the software for the video camera itself. I just need to capture this feature in my application. Also, my problem is how will my application know which is that program that it should invoke (either for a scanner or a web cam or a video cam) . I cannot hard-code the name of the exe because the scanning software will differ from scanner to scanner. I have never used graphics to such an extent and am absolutely clueless about the whole thing. Any little help on this one would be highly appreciated. Thank You All in Advance .