I remember exactly when the last version of Qt is 3.3.6, I downloaded opensource form Qt's website to compile with MingW but failed (i don't remember errors). Then I search on internet, and found website: http://sourceforge.net/projects/qtwin/. I tried download it and compile successfully. Right now, I don't find version 4.2 on http://sourceforge.net/projects/qtwin/. If I download version 4.2 from Qt'website, I think I also have errors when compiling same as 3.3.6.