Yes, by selecting a classic skin (or any other 3rd-party classic skin) in Winamp 5.0.
Winamp 5.0 is the direct upgrade from 2.9x, built on the same engine.
hmm . . . just reading between the lines...
Yes, Winamp 2.91 did have a media library, very similar to Winamp 5.0's, except it was a much older & more primitive version. It's the same media library in 5.0, except much more advanced, developed and feature rich. Oh, I give in