Windows 7 works like a charm on its second day since installation on my wife's Fujitsu Siemens' ESPRIMO Mobile U9400 UMTS powered by Intel's Core 2 Duo Processor 965gm Intel Chipset (2.1 GHz) with 2.0 Gig Ram. Its pre-issued drivers for Vista works perfectly on the new found Windows 7.
I noticed that the new operating system is energy efficient, it provides a rich set of energy saving features. Through reduced background activity by minimizing the number of services running at startup, the number of disk operations, the reading and writing to and from the the registry, and the indexing of files, Windows 7 increase the performance of the operating system but also to consume much less energy.
It is a very impressive performance of Windows 7 on its Beta issue which will surely put it ahead of Windows Vista SP1. Why don't you give it a try.