Windows 7 netbook system specs explained
Over 1GB of that footprint in Vista is pre-installed drivers, and Windows components add another 500MB. Microsoft doesn't plan to reduce those much, but Sinofsky says the beta of Windows 7 will extend the list of 'optional components' which are installed but not loaded by default.
Even in the pre-beta this is much more granular; you can remove XPS support, gadgets or tablet features. Even if you have tablet features loaded, the component won't actually be in the memory unless you have tablet hardware on your PC. (Source: Mary Branscombe, TechRadar.com)
Chris De Herrera