Whilst I was researching ways of resizing my partition on Vista, without destruction of data (hopefully), I was pleased to hear that Vista had its own system for doing it. So I tried disk management, and, of course, it failed to do anything even the least bit constructive. There was some recommendation about pagefiles and backups, both of which I checked and they seemed to take up minimal room.
So, I gave up and tried making a GPartition Live CD, booted, made the appropiate changes and a couple of hours later my Dell PC’s Vista partition was smaller. There was a small problem with Vista’s booting process, but, to Vista’s redemption, it managed to repair itself.