Windows Vista, which will enable PC buyers to see how well a particular model can handle the new operating system. The tool ranks your computer on an overall scale of 1-5, and ranks specific components as well. The tool is likely to benefit PC retailers, who will be able to use a relatively low score as a rationale for selling upgrades, but it could also leave some consumers bewildered by what may seem like mediocre scores for relatively high-end systems. Trying out the new system on a number of PCs, CNET found that a recent Sony Vaio with a 1.83GHz Intel T2400 and 1GB of RAM scored a middling 3, though the rating system gave it a whopping 5.6 for its processor and 5.5 for memory. In the meantime, Microsoft is also preparing another tool, the Windows Upgrade Advisor, which will allow computer owners running Windows XP to find out whether their computers have the right stuff to use Vista. If it's anything like the Performance Rating, we assume it'll tell you to install major upgrades, even if you're running the latest $5,000 Quad SLI, 2GB RAM, Athlon 64 gaming rig.