Why does the /winsxs folder grow so large, and can it be made smaller?

Problem

A Vista virtual machine I use only has a 10 GB virtual hard disk -- and I'm worried about it running out of space over time. I used TreeSize to check for the culprits.. And the primary culprit is that or "Windows Side-By-Side" folder. What is the Windows Side By Side folder? Well, that's explained pretty well here. All of the components in the operating system are found in the WinSxS folder – in fact we call this location the component store. Each component has a unique name that includes the version, language, and processor architecture that it was built for. The WinSxS folder is the only location that the component is found on the system, all other instances of the files that you see on the system are “projected” by hard linking from the component store. Let me repeat that last point – there is only one instance (or full data copy) of each version of each file in the OS, and that instance is located in the WinSxS folder. So looked at from that perspective, the WinSxS folder is reall…