Do I need to reinstall the utillity drivers disk that came with the machine?
Good chance that Win7 is using a generic mouse driver. So installing the correct Dell driver should get the touchpad tab like your 2nd laptop.
You should be able to compare the driver versions and then get just the driver you need off the Dell Support site.
I'd go for just the one driver you need off the website instead of trying to use the CD with might be out of date.
If there are no Win7 drivers try the Vista version (32bit or 64bit depending on which ver of Win7 you have installed)