I have just bought a 2001 Octavia and when I am accelerating it is all good but when i take my foot off the throtle I am getting a whining noise, but when i put my foot onto the clutch the noise goes away, When I bought the car i was told that they had put a new clutch into the car and damaged the thrust/release bearing but think it could be the gear box after speaking to a few people, has anyone any ides if this would be correct and also if i need a new gearbox were would be the best place to get a re-conditioned one.

That sounds like a thrust bearing to me.

You might struggle to find a recon box for one of these cars though.