Kontakt libs open only in Kontakt, as far as I know. Some libraries include the samples as wav files, which you can load into Kontakt - you'd have to look and see if those are yours. Of course, you'd have to program DimPro or any other sampler w/ those.
The Kontakt player is free, but some 3rd party libraries will open only in "demo" mode - so you have 15 minutes to do any work w/ them before the player shuts down w/ them. If you have a Kontakt library(ies) (that comes w/ the player), that/they will be fully functional in the player.
So it is kinda of a crapshoot unless you plunk down for the full Kontakt. I would try the free player w/ your libraries and seeif they work before deciding between Kontakt or DimPro. DimPro, if not as universal w/ libs as Kontakt, has its own charms and is a hell of a lot cheaper. And if you spring for the full Kontakt, you'll be buying more libs most likely.
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