I'm doing some computer maintenance, changing up my partition layout, so like a good GNU fan I'm using GParted. A wonderful product... however, I happened to grab an old copy from my CD Wallet. There were two in there, and I thought it was the newer one... I was wrong. The version I used was < 0.3.5 - and so it had a tiny 'bug' that caused things to run very slowly when performing the step it called "move filesystem to the right". During this time, 'top' showed that the a single thread was using as much CPU time as it could get (50% in the case of my dual-core system). I was moving ~400GB partition with about ~350GB of data. It took about 36 hours on my 1.6ghz with a new-ish 1TB SATA drive. So, if anyone finds themself in this tricky situation... wait it out, it does eventually work, and there's not really anything you can do in the meantime to abort the process without losing your data. Hopefully your system is on a UPS in case the power drops for a moment (always a good thing when moving data around - of course, hopefully you backed it up first too).