Qt 4.8 (which is the latest version at this moment) definitely works on Windows XP. It's even one of the "Tier 1" platforms: In my experience, Qt works just fine, even on good old Windows 2000. And, with a little help of KernelEx, Qt-based applications even run on Windows 98 SE ;) However if you use VS2010 as compiler, some workarounds are required for Windows 2000 as well as for Windows XP prior to SP-2 - not because of Qt, but because of VS2010's CRT libraries. BTW: If an application uses the "shared" Visual C++ Runtime, but the required runtime components are not installed, you should see an error message about a missing DLL file...