Need to make my project file work on both Windows 7 and Mac 10.6

I have written all of my code on a windows 7 environment. I now need to port it Mac OS 10.6. The first questioin is how to fix my project files. RIght now I have sections of the project file that looks like the below code. But since Mac's do not have a C drive and the paths are different, what is the correct way to make my project files work on both environments?

Code:

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QT       += core gui network qwt webkit
 
 
TARGET = eP1
TEMPLATE = app
 
RC_FILE = eP1.rc
 
 
QWT_DIR = C:/qwt-6.0.1
INCLUDEPATH += $$QWT_DIR/include
INCLUDEPATH += C:/Temp/QT_Projects/qextserialport/src
INCLUDEPATH += C:/Temp/QT_Projects/minimoog-QTweetLib-2129f91/src
 
VERSION = 0.987
DEFINES += "MAJOR_VER=\"0\""
DEFINES += "MINOR_VER=\"987\""
 
 
include(C:/QtSDK/Desktop/Qt/4.7.3/mingw/qtsingleapplication/src/qtsingleapplication.pri)
 
SOURCES += main.cpp\
        mainwindow_ep1.cpp \
 
....
 
OTHER_FILES += \
    ep1_logo.png \
    index.html \
    main.js
 
QMAKE_LIBDIR += C:/Temp/QT_Projects/qextserialport/src-build-desktop/build
 
QMAKE_LIBDIR += C:/qwt-6.0.1/lib

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