For reference only
Sometimes there's a delay before Finder shows the true amount available.
At http://www.wuala.com/grahamperrin/publi ... allery&id= for example, a succession of three screenshots, the first of which was taken after some snapshots were destroyed.
Whilst Disk Inventory X showed 40.1 GB free, Finder showed 11.46 GB available.
Later, Finder showed 42.99 GB available.