Step one is to concatenate fragmented VMWare images. This might not me necessary in your case, but we’ll do it anyway. Let’s assume the image you want to convert is called leopard-fragmented.vmdk:

Now you’re got a rather huge VMWare disk image file, and we’ll use qemu to convert it into a raw disk image:

This will take a while, and you’ll probably end up with a less-than-huge file since this is the raw file, without any fancy compression. Now you’ll want to convert this to the VirtualBox disk format, vdi:

The vdi ended up being around 7GB – more or less the exact size of the vmdk file. The temporary bin file was 32GB though. Be sure you’re got enough room on your disk for this job.