I'm developing some software for Windows and trying to decide which version of Windows I should target as the minimum requirements. For those non-programmers, this is a factor because newer versions of Windows provide new functionality at the API level (ie. the functions you can call from code) which can make programming easier. However, by using this new functionality, you restrict your app to running on the OS where it was introduced, along with all new OS's (eg. if the functionality was introduced on Windows 2000, then the app would only run on Windows 2000, XP, Vista, Server 2003, Server 2008 etc.). I've read the two existing polls, Windows OS poll 2008 home and Windows OS poll 2008 work, where the results indicate over 95% of people are using XP or Vista (for both home and work). I was originally planning on targeting Windows 98 as the minimum level, although this requires more effort to support. Then I was swaying towards Windows 2000 (as this has some decent extra functionality for the programmer), but now I'm considering XP as the minimum. What Windows OS should I be targeting as the minimum requirement for my new software apps ? Thanks in advance for your help!