I would just add a couple of more nines to that 99.9%.
http://www.ornl.gov/sci/techresources/Human_Genome/project/i...
I'm also wrong about the chimpanzees - recent research suggests that they share only 95% of genes with humans, not 98% - but at least I'm not off by a few orders of magnitude.
In any case, that number's backed up by several sources:
http://abcnews.go.com/Technology/story?id=99478&page=1
http://news.nationalgeographic.com/news/2002/09/0924_020924_...