The Inq played with Windows Vista and noticed the Windows Experience Index tool isn't really accurate:
We upgraded system with around €450 worth memory, a brand new graphic card Radeon X1950 XTX that costs roughly €399, a Seagate Barracuda 7200.9 500GB 16MB SATA II drive that costs just over €200 and a CPU that costs around €270. What did we gain from Microsoft performance tool just a lousy non realistic few points. Trust me Vista works much better with these new components and €1300+ new hardware will really make a stand out difference. Unfortunately not according to this Microsoft performance tool.