We have bought Finale 2007 and the sounds are particularly bad. Is there any possibility to get a better sound on the programm itself. Please help us. Thank you very much.

Finale will play any audio units plug in. I use the garritan big band, Kontact 3, and the garritan orch player that comes with the app.
you should probably cx to make sure you're at least using the garritan player sounds that ship with the app. they're not amazing, but i wouldn't describe them as "particularly bad." i bet you're playing some cheezy quicktime sound set.