I just bought
Quick View Plus Standard Edition. This is a file viewer that utilizes Oracle's
Outside In technology. I was afraid to get it because of reviews that say it takes over your computer and floods you with nag screens. The part about the nag screens is true. With the trial version I was getting them so often I was not sure I could give it a good test. But I managed. And the main selling point to me was that it integrates with Directory Opus and Windows Explorer to work inside their preview windows. Nice to be able to see my WordPerfect stuff using a file manager.
Anyway, there are free tools that use the same technology, but I'm tech-weary and I thought it would be easier to just buy this and let the publisher worry about updating it.