Benchmarking the Chromebox is a challenge because of its closed software ecosystem. Really, browser-based tests are our only option. Even these are imperfect, though. Although we can use the same browser on each platform, Chrome OS and Windows 7 are also variables in play. Nevertheless, our benchmarks should help illustrate each system's real-world performance.
The V8 Benchmark Suite was created by Google specifically to test the performance of its Chrome browser.
BrowsingBench was created by EEMBC, also known as the Embedded Microprocessor Benchmark Consortium. It's a non-profit organization tasked with finding ways to develop testing methodology, specifically for embedded hardware. We're been playing around with this tool in the lab, and we love it. While it's meant for testing "smartphones, netbooks, portable gaming devices, navigation devices, and IP set-top boxes," it's just as applicable for testing browser performance in general.