Why can't I preview WordPerfect files? And why is the preview of files SOOOOO SLOW 
compared to Powerdesk which is instantaneous? Seems like opus has to load and reload some viewer dll EVERY time you view a file even of the SAME TYPE (e.g., doc, pdf, xls). This is exasperating. For this alone, I'd much rather use POWERDESK!
BTW, I have Windows XP sp2, pentium 4, 512 ram
You can use the Multiview plugin to utilise the same viewers as Powerdesk. Simply configure it to use the folder containing the viewer dlls. Alternatively you can download the viewers as part of the Yahoo Desktop Search.
If you want to know why the default viewer is so slow with those file formats it is because it loads Word, PowerPower, Excel themselves to display the files. (Or OpenOffice if you have it installed. It seems to load much faster than the bloated Office apps.)
The viewer technology that the MultiView plugin hooks into doesn't load any of the office apps; instead they've written their own lightweight viewers by reverse-engineering the Office file formats.
Opus lets you chose which of the two technologies you want to use, although it sadly doesn't ship with the DLLs required to make MultiView work, due to licencing/cost issues. You can get them for free, though, as Tanis mentioned.
I activated multiview but where do I browse for the viewere plugins? I tried to browse to my Powerdesk folder but the OK button won't work.
Hopefully someone who has Powerdesk installed can point you to the correct folder - I do know it's the one full of dll files though if that helps.
YES! Much faster viewing now that I installed Yahoo desktop search. Had to include the viewer expansion pack to view my wordperfect docs. I also disabled ActiveX viewer which seems to slow down the viewing. (Still couldn't locate powerdesk's viewers though but never mind.)
Thanks a lot tanis and nudel! much respect!
If you disable the ActiveX viewer then a bunch of other formats will no longer be viewable, which may not be what you want.
Instead, move the plugins around using the Up/Down buttons so that the MultiView one is above the ActiveX one. Then the ActiveX viewer will only be called for formats which MultiView cannot handle.
You could also configure the ActiveX plugin and remove .doc (etc.) from its list of handled extensions.
Ah yes! thanks again!
Correction: You can't move ActiveX below MultiView or vice versa, but you can still edit the list of extensions.
Well now, I can say that Opus is far, far better than Powerdesk! 
This forum's a great help. and fast replies too!
I checked out pretentiousname.com and saw the helpful tutorials. will dig deeper into Opus's powers!