PerfectUpdater finds up to 29 driver updates for my XPSOne, which are even not listed on Dell website. Works great. Its driver backup feature keeps me safe when updates fail or other errors occur.
I installed PerfectUpdater but had trouble in launching it. So I contacted customer support. I have to say I get nothing helpful from the customer support, and could not get a response from them any more after several contacts.
I gave it a try and it basically updated all my drivers to the latest version. Nothing goes wrong so far.