WARNING! WARNING! FUD LEVELS APPROACHING HAZARDOUS LEVELS!
OK, first off, I am pleasantly suprised by the lack of Vista issues so far in it's lifespan.
That being said, this report is a load of horse puckey.
You can't make comparisons like this. Comparing security vulnerabilities is not a simple apples-to-apples comparison. Comparing "Oh, someone can crash your solitare session in Ubuntu by misforming a configuration file" to "Oh, someone can execute code if you look at an image file" is just plain stupid. Both are security issues, yes, but the severity of the two bugs is like night and day.
There is also the problem of "undisclosed" bugs. IIRC, Microsoft will not give you "credit" for finding a security hole if you disclose the bug before they patch it. This means there could be a bunch of holes in the pipeline that haven't been disclosed to the public yet (but could still be exploited by less scrupulous people). I think there is some company someplace which has a list of security issues disclosed to microsoft and how long they've been sitting on them. However, I forget who.
There is a great debate to be had over who is "more secure." Sadly, this report does nothing but spread FUD.