Did you install the drivers in the correct order? See the following:
http://support.dell.com/support/topics/global.aspx/support/dsn/en/document?journalid=4ED81717490911DC84EB0DC67E2C6D57&docid=3690A8CC21FAF290E040A68F5B281A12
It is absolutely essential that the Notebook System Software and the Chipset drivers be installed before even attempting to install other device drivers. All drivers for you system can be downloaded from the Dell download site for your model:
http://support.dell.com/support/downloads/driverslist.aspx?c=us&l=en&s=gen&ServiceTag=&SystemID=INS_PNT_PM_600M&os=WW1&osl=en&catid=&impid=
Steve