Auto WMV Video Screen Cap Generator

I want a program to be able to process a WMV file and generate video screen caps in uncompressed JPG format every 30 seconds in whatever resolution the video is in. So for example, lets say I have a 10 minute 640x480 WMV video file. After running the program it will automatically generate (20) 640x480 JPG files. the 30 second interval should be adjustable but defaulted to 30 seconds.. also batch processing of many WMV files is a must. must have progress bar to show status of process.