About 600 Gig, counting my USB2 External HD too (3x200Gb)
free... about 80 I think, which won't be enough come next lan-party, arf!
time to buy myself another one I think
Ideally: enough to never run out of diskspace... But if you rarely throw things away, that's a financial problem... I might be ok with a 2-3 TB for a few years (hopefully)