I work for an employer still firmly rooted to XP on our desktops and I've seen the gluttony of Vista on my wife's computer so when I purchased my last laptop I had it downgraded to XP Pro.
I work hard to keep my laptop configured for maximum battery life. I minimize the resources that startup when the computer boots and configure separate accounts for work and play so I'm not running SQL server while I'm trying to watch a movie and MSN isn't distracting me while I work.
My employer indicated intent to migrate to Win 7 in the next 18 months so I snagged a copy of Win 7 Ultimate X64 and installed it on an eSATA drive for my laptop. I didn’t want to upgrade yet because I was afraid it would affect the battery life and rather than deal with dual boot I just installed it on an external drive since I assumed I would still use XP on a daily basis.
Oddly enough after the basic install patch of Windows 7 and my standard software suite (Office 2007, Visual Studio 2008, and SQL Server 2005). I was seeing only a minor increase in memory usage and a decrease in idle processor usage. After I finished configuring my accounts like I had done in XP I noticed both accounts ran a lower memory profile than XP, and the idle processor load appeared lower as well.
While there is a difference between a fresh install and a system that's been running for over a year I was shocked to see the idle load at less than 1.2 GB and 4% processor load. My wife's computer which is running Vista X64 has an idle load of 2.4 GB and 7%, and she's got a quad core to my dual. She’s not running IIS or SQL Server either.
Since my discovery I have swapped the external HDD for my internal one. I've been using my laptop under Win 7 for about two weeks and I haven't seen the change in idle load translate to a significant increase in battery life. I assume that the difference is being consumed by my graphics card in order to make everything so damn pretty. Most important is that I haven't seen a decrease which is why I resisted the move so far. I like the added security and better resource management, I even like the pretty. It's nice to know when Microsoft said they improved the power consumption there was actually a significant improvement.
IT Infrastructure Consultant
Nothing is more confounding than a DBA that uses bureaucracy as a means to inflate his power. Ever try to get an index added to a government run SQL server and you'll know what I mean.