Rotating videos

I recently took some videos in portrait mode with a digital camera but, after transferring them to the PC, they play in landscape mode, turned anticlockwise 90 degrees. This happens with either WMP, WMC or VLC. Anybody know how I can rotate them 90 degrees clockwise ? In VLC I've tried the rotation option in settings but it has no effect.
Thanks for any help.

you can use the windows movie maker which built in windows.

The youtube video below is on How to Rotate a Video in Windows Movie Maker

http://www.youtube.com/watch?v=HlqqlS8CDv4

Thanks Michael, I'll give that a try later on when I get home

That worked fine Michael, thanks a lot - John