Laptop Magazine has some surprising news for Windows 7 battery life, at least on three netbooks: It's not as good as it was on XP. Here's what they found:

Back in August when we started testing the final version of Windows 7, we noticed that several netbooks didn’t last as long on a charge with the new OS installed as with Windows XP. Microsoft claimed that Win 7 notebooks would see longer battery life than Vista, and for the two full-size systems we upgraded that rang true. The Dell XPS Studio 16 only got an extra few minutes, but the Gateway NV lasted an extra hour. Netbooks have been a different story.

Recently we tested Windows 7 versions of the Toshiba mini NB205 and ASUS Eee PC 1008HA, and now  HP’s Mini 311 with Windows 7 has been released. The results don’t look good. In each case we tested the three systems using the LAPTOP Battery Test (continuous web surfing over Wi-Fi) and in each case the Windows 7 machines got less battery life.

What's interesting about this is that netbooks are one of the few ways in which to accurately test Windows 7 battery life vs. that of XP, since this is the only market where you can find the same machines in which both OSes have been included. With mainstream laptops, the battery life differences (between Vista and 7, in that case) seem to be less dramatic.