i recently reinstalled vista from my computer manufacturer's cd and had to spend a long day redoing all the updates (up to sp2) manually and sequentially -> would there be any way to create/buy/copy a cd that would automatically install vista up to the last update installed on any given machine?

I had seen an SP1 disk but not yet an SP2. But you could also slipstream one yourself - although that is probably as much work as an installation. The easiest is to image your system with Ghost, Acronis or the free Macrium. That takes little work and allows you to reset to the image any time.

Macrium has a free version. And here is some more information.