Somehow I ended up with opus as the default viewer for jpeg images. I would like to go back to the viewer built into windows xp. I can't find any preference for this.
Wow, I just purchased Directory Opus last night and my first forum entry. 
Go to Preferences - Double-click - Files and uncheck "Use internal picture viewer".
Jeff
But how can I set the Opus image viewer to re-size the picture to screen size if it is bigger than screen size?
You can press the hotkey O to make the image full sized, or F to fit it on the screen.
There's also the icon buttons at the bottom of the viewer which do the same thing.
Is there no way of setting Opus to re-size by default? Almost all my digital images are much bigger than the screen resolution so I would have to resize every one. Much easier to have it the other way - resize by default and make it original size if required.
Preferences - Viewer - Viewer(Standalone)
Then check the option:
Reset zoom level for each picture to
Change the dropdown to Fit to page
Maybe setting Preferences->Viewer->Viewer (Standalone)->Reset zoom level for each picture to to Fit To Page?
On my 24" lcd almost every image is too small.
I think fit to page only reduces the size of the image.
Original size and fit to page are the same for me.
I think I have tried every combination of options....
You have to zoom in manually, which is a pain because if you change to a large image you then have to zoom out or fit-to-page manually.
I would also like a "fill page" mode where large images are reduced and small images are enlarge to fill the window.
If you uncheck 'Preferences/View/Auto-size Viewer window', DOpus internal viewer will remember the last frame size you set. I have 'Fit to page' checked, too, not sure if this matters. Still use IrfanView though.