The soundtrack is comprised of four CDs -- Gundam Wing Operations 1-4.
Operation 1: This CD is almost entirely instrumental, with only two of the *forty* tracks being vocals (the opening and ending themes, "Just Communication" and "It's Just Love!"). The music is mostly classical in nature and perfomed by a full orchestra, with an electric guitar or two often added for good measure. ^_^ If you could only own one of the four CDs, I'm pretty sure this is the one you'd want.
Operation 2: Heh, all of the G-boys turn songbird on this one. Too bad Hiro couldn't sing to save his life. Duo sings "Good Luck and Goodbye" (a personal favorite o' mine), Wufei yodels an odd, but not unpleasant, rock song, Trowa croons a sweet, sad tune, and Quatre... well... Poor Quatre is forced to sing a wild rock 'n' roll type gig, and it ends up being cute, yet vaguely horrifying. That's the best way I know to describe it. x_x The rest of the tracks are instrumental and every bit as good as the ones on the first CD -- there just aren't as many of them. The TV-sized versions of the opening and ending themes are also on this CD.
Operation 3: Like the second CD, this one is a mixture of vocals and instrumentals. Relena, Lady Une, and Dorothy contribute respectable performances, Duo sings a happy-fun song, and Hiro AGAIN attempts to carry a tune, with mixed results. Unlike Operations 1 and 2, which included some frantically-paced, action-oriented tracks, the instrumentals on this CD are more moody and atmospheric. It's a nice change of pace, overall.
Operation 4: This one is pure vocals, mostly performed by the cast members. Zechs and Treize get to sing on this one, and do a fine job of it, too. Duo gets a cool rock song, Trowa and Wufei sing fast-paced ditties, and Quatre gets a slow, soothing ballad this time around, thank heavens. Even Hiro manages to belt out a decent tune with "Flying Away." This CD's a must for all true GW fans.
And now... the clips!
Track 13 -- a soft, wistful tune
Track 20 -- a COOL melody (I always think of Trowa when I hear this)
Track 27 -- another soft, slow track