The legend should sound pretty familiar by now: The oft-brilliant country/ roots/alternative band Uncle Tupelo broke up in 1994, breaking the hearts of its cultish following. At that point, two offshoots formed (Jay Farrar's Son Volt and Jeff Tweedy's Wilco), each making a record that amply represented one of the two wonderful sides of Uncle Tupelo. (Son Volt turned out a set of forlorn, countrified, ragged ballads, while Wilco made more clear-sounding, twangy rock songs.) You could put Wilco's A.M. and Son Volt's Trace in a disc-changer, hit random-play, and have yourself a great Uncle Tupelo double-album. Now, two years after Tupelo's demise, there's a great Wilco double-album, a 19-song set that finds Tweedy dipping more generously and ambitiously into the wells of country, pop, roots and all-out rock and roll. Those innately cynical of double-albums needn't worry about overlength: At 76 minutes, Being There could've fit on one disc, and the package lists at the same price as regular CDs. And fans will be thrilled to hear Wilco roughing up its trademark sound and getting a bit more adventurous, moody and dissonant throughout this fine new album.