Cant update hardware on xp pro

Go to the link here, and select the needed driver from the appropriate category.
http://support.dell.com/support/downloads/driverslist.aspx?c=us&l=en&s=gen&ServiceTag=&SystemID=INSPIRON%201200&os=WW1&osl=en&catid=&impid=

Once you've downloaded them, just extract the files, and run the setup program.