Whirling sound when I press the clutch

The thrust bearing is probably failing. It is always good to go with a new clutch and the work involved is just the same and you do not want to be pulling the transmission again in the near future if the clutch starts to slip. There is a good chance that the clutch as well due for replacement anyway. Also, make sure that you get the fly wheel re surfaced and replace the spigot bearing in the back of the flywheel. Do it all now and you w ill not have a problem for years as far as the clutch is concerned.