So to solve my Vista installation problem I got hold of Disk Director from Acronis. I've been using their True Image product for a while and have loved it; it's invaluable for making backups of entire partitions and is especially suited to people like myself who reinstall their laptop regularly. Disk Director is no less useful and allowed me to resize my partitions without having to reinstall anything. It's one of the nicest programs I've used, with a simple wizard that walks you through which partition you want to expan and where the new space will come from. What I particularly like is the final step, which outlines the steps it will take, indicating when it's going to reboot.
So, with enough space, the upgrade to Vista took a couple of hours and everything is now new and shiny.