An external HDD can be used to play files on PS3. Check the PS3 support site for the type of files supported. "Handbrake" is a 5MB download from the net which will convert most anything you can throw at it into a format the PS3 will play.
A Google search will tell you how to format the external HDD so the PS3 recognizes it.
Thanks Homer,
I will download that and try it out. My PS3 is up and running well, reading all files on my PC (pic. videos, music) and playing them all very well. Just videos encoded in .flv format are not accepted. As I mentioned before I could not find a Windows codec to install in WMPlayer to be able to pay those files on my PS3. What I read on Handbrake's web page, it does not look like that they translate .flv files; but I wil try it nevertheless.
Tony