'drivermagic', & driveragent.com'
I've always trusted my driver updates to my own hands. Their promises on the front page sound pretty nice: "keep your computer updated, takes less than 5 minutes to find your computer's missing/updated drivers,..." Don't know what harm could it do to try these, BUT they tend to have some sort of trick to it: Scanning or searching is free, but downloading the drivers or actually seeing the results is not.
I'd recommend skipping the subscriptions to these "life made easy" services and just checking once in a while if there are new driver updates available at hardware manufactorer's own sites. If your system works smoothly, there's no actual need to update, since it may do worse with the new drivers.