I've been using XP, even with dual boot option for Win7, because my laptop kinda didn't support Win7, because a USB driver made my keyboard act horribly (see the forum post Keyboard Repeats Uncontrollably). Specifically, I have been messing with windows embedded standard 7, not Win7, but I had the same issue as described in that forum. I never found a solution, even trying on and off for years. Then just recently with Snappy Drivers, I found that installing their drivers solved the issue, specifically the PCI Class USB 2.0 Enhanced Host Controller (watch for the expansion arrow for a drop down list, which have to be selected separately!).
So now I have both XP and 7 working pretty well, and while 7 is slower, it's all about the web browser these days. The web browser is the new OS, and what matters most if you are going to stay up-to-date.