Join Date: Jan 2003
Bikes: Bianchi 928, Bianchi Pista Concept 2004, Surly Steamroller, 1998 Schwinn Factory Team Homegrown, 1999 Schwinn Homegrown Factory, 2000 Schwinn Panther, Niner EMD9
Velocity rims are good, but I'm partial to the Suns. Rhyno Lites are an excellent choice. Some people favor the 32 hole as the three cross lacing allows for more parallel alignment of spokes, thus theoretically resulting in a stronger build than a 36. YMMV.
XT hubs are great-nothing fancy, not too expensive, and easily and economically rebuilt.
EDIT: As others have said, it's the handbuilt quality that makes the big difference. A lousy build on the best rim out there isn't going to do you any good.