It would help the Western cause to have Serbia join NATO, with eventual membership in the European Union in the not too distant future. Any likelihood of the former happening, or is Serbia going to have to remain in its current stasis?
There is one big obstacle to Serbia's integration, and that's Kosovo. It would take a while to get reconciled with the territory's loss, and until that happens Serbia will stay an odd man out. What has to be done is putting out a clear road map to Serbia's integration into NATO and the EU, accompanied by credible commitments to help the country en route (naturally, accepting Kosovo's secession and cooperating on the war criminals would have to be there, but so should other things, to make it all more palatable). Furthermore, EU and NATO should continue on with integrating Croatia, Montenegro, and, later, Macedonia, Bosnia, Albania and Kosovo: the example of the neighbors is going to be very valuable here.