Another downside is that it tends to screw up from time to time. I remember gore and his wife had trouble with Windows update a few weeks ago. A friend of mine had problems with the same update as it "lost" his Windows partition, and a whole load of files.

Fortunately he had a linux distro and recovered his files but he ended up reinstalling Windows.

I guess that if the browser actually checks for an update, rather than just having it squirted at you out of the blue, it will be reasonably safe. Provided, of course, it rejects any update it didn't initiate.