I upgraded from 80GB to 250GB today. Although I still only have an 80GB partition, so not 100% succesful. But I didn’t lose data. I used dd, and my Linux box, which had two spare SATA ports.

Simply remove the drive from the macbook.

Connect both drives to the Linux box when off. Boot. Examine which one is which by mounting them separately. Then dd in this manner:

dd if=/dev/sda of=/dev/sda bs=1024k

Leave 2 hours, put the new drive in the mac and boot. Sorted.

Now I’ll go home copy stuff I want to keep to another disk and reinstall OSX.

I know this guide is hardly useful, but someone needs to put some info out there. Comment if you want more details or have some tips.