I downloaded Qwt 5.2.0 from source forge, and unzipped it to a folder.
I editted the qwtconfig.pri file to point to this folder and tweaked the other items as I felt were necessary.
I have tried to build qwt from a command prompt as well as from within qt creator 1.3.1 but both fail and I am stumped.

Command prompt:
I launch a command prompt from the Qt 4.6.1 (open source) menu which seems to setup all the correct variables. Then without changing folders I type qmake /my qwt folder/qwt.pro and get no feedback. I then type make and it chugs away for awhile but eventually fails and I get the following (last few lines only):

c:\projects\libraries\qwtlibs\qwt-5.2.0\src\/qwt_valuelist.h:48: instantiated
from here
..\include/QtCore/../../src/corelib/tools/qhash.h:875: error: call of overloaded
'qHash(const double&)' is ambiguous
..\include/QtCore/../../src/corelib/tools/qhash.h:62: note: candidates are: uint
qHash(char)
..\include/QtCore/../../src/corelib/tools/qhash.h:63: note: uint
qHash(uchar)
..\include/QtCore/../../src/corelib/tools/qhash.h:64: note: uint
qHash(signed char)
..\include/QtCore/../../src/corelib/tools/qhash.h:65: note: uint
qHash(ushort)
..\include/QtCore/../../src/corelib/tools/qhash.h:66: note: uint
qHash(short int)
..\include/QtCore/../../src/corelib/tools/qhash.h:67: note: uint
qHash(uint)
..\include/QtCore/../../src/corelib/tools/qhash.h:68: note: uint
qHash(int)
..\include/QtCore/../../src/corelib/tools/qhash.h:69: note: uint
qHash(ulong)
..\include/QtCore/../../src/corelib/tools/qhash.h:77: note: uint
qHash(long int)
..\include/QtCore/../../src/corelib/tools/qhash.h:78: note: uint
qHash(quint64)
..\include/QtCore/../../src/corelib/tools/qhash.h:86: note: uint
qHash(qint64)
..\include/QtCore/../../src/corelib/tools/qhash.h:87: note: uint
qHash(QChar)
mingw32-make[2]: *** [obj/qwt_plot.o] Error 1
mingw32-make[2]: Leaving directory `C:/Qt/4.6.1/src'
mingw32-make[1]: *** [release-all] Error 2
mingw32-make[1]: Leaving directory `C:/Qt/4.6.1/src'
mingw32-make: *** [sub-src-make_default] Error 2

And I have no clue what to do. I have tried search on the net and forums and have found no clues.

I then tried from within QtCreator:
As I have VS2003 as well as other version of Qt installed on my PC I wanted to make sure that the correct environment variables are set, so I again ran the 4.6.1 command prompt and launch QtCreator from this. I then browse to and open qwt.pro and build it and get the following:
Running build steps for project qwt...
Starting: c:/qt/4.6.1/bin/qmake.exe C:/Projects/Libraries/QwtLibs/qwt-5.2.0/qwt.pro -r -spec $(QTDIR)\mkspecs\win32-g++ -tp vc QMAKE_INCDIR_QT=$(QTDIR)\include QMAKE_LIBDIR_QT= QMAKE_LIBDIR=$(QTDIR)\lib QMAKE_UIC=$(QTDIR)\bin\uic.exe QMAKE_MOC=$(QTDIR)\bin\moc.exe QMAKE_RCC=$(QTDIR)\bin\rcc.exe QMAKE_QMAKE=$(QTDIR)\bin\qmake.exe
Reading C:/Projects/Libraries/QwtLibs/qwt-5.2.0/src/src.pro
Reading C:/Projects/Libraries/QwtLibs/qwt-5.2.0/textengines/textengines.pro
Reading C:/Projects/Libraries/QwtLibs/qwt-5.2.0/designer/designer.pro
WARNING: Unable to generate output for: C:/Projects/Libraries/QwtLibs/qwt-5.2.0/src/Makefile.Release [TEMPLATE vclib]
WARNING: Unable to generate output for: C:/Projects/Libraries/QwtLibs/qwt-5.2.0/src/Makefile.Debug [TEMPLATE vclib]
WARNING: Unable to generate output for: c:/Projects/Libraries/QwtLibs/qwt-5.2.0/textengines/Makefile.Release [TEMPLATE vcsubdirs]
WARNING: Unable to generate output for: c:/Projects/Libraries/QwtLibs/qwt-5.2.0/textengines/Makefile.Debug [TEMPLATE vcsubdirs]
WARNING: Unable to generate output for: C:/Projects/Libraries/QwtLibs/qwt-5.2.0/designer/Makefile.Release [TEMPLATE vclib]
WARNING: Unable to generate output for: C:/Projects/Libraries/QwtLibs/qwt-5.2.0/designer/Makefile.Debug [TEMPLATE vclib]
WARNING: Unable to generate output for: c:/Projects/Libraries/QwtLibs/qwt-5.2.0/Makefile.Release [TEMPLATE vcsubdirs]
WARNING: Unable to generate output for: c:/Projects/Libraries/QwtLibs/qwt-5.2.0/Makefile.Debug [TEMPLATE vcsubdirs]
Exited with code 0.
Starting: C:/MinGW/bin/mingw32-make.exe -w
mingw32-make: Entering directory `C:/Projects/Libraries/QwtLibs/qwt-5.2.0'
C:/MinGW/bin/mingw32-make -f Makefile.Release
mingw32-make[1]: Entering directory `C:/Projects/Libraries/QwtLibs/qwt-5.2.0'
mingw32-make[1]: Leaving directory `C:/Projects/Libraries/QwtLibs/qwt-5.2.0'
mingw32-make: Leaving directory `C:/Projects/Libraries/QwtLibs/qwt-5.2.0'
mingw32-make[1]: Makefile.Release: No such file or directory
mingw32-make[1]: *** No rule to make target `Makefile.Release'. Stop.
mingw32-make: *** [release] Error 2
Exited with code 2.
Error while building project qwt
When executing build step 'Make'

I am very new to MinGW and to QtCreator so I am stuck and any help would be much appreciated.