I have a Dell XPS M1530 and I had the same troubles.
I downloaded it from Dell's website and it crippled my touchpad. So, I plugged in a USB mouse and uninstalled the software and it uncrippled it. I then tore my house apart to look for my Driver CDs that came with my laptop three years ago. I found it, installed it from the CD and lo and behold, touchpad now works!!!
Odd that the one on Dell's site didn't work. I notice the one on Dell's site is a newer version, so maybe my touchpad needed the older version. Weird.
I have installed WIndows 8 RTM twice: From a leaked version and the proper upgrade.
At first, I did some magic tricks to make the touch pad working. Then, at the second install, no matter what I did, it wouldn't install.
So, what I did, is that I got some Inspiron touchpad drivers (since it seemed to be the same device) and boom, it was working better than ever! I can side scroll (something I lost after my first Vista format, 4 years ago)