Interesting....

[paper_lanterns]

Mozilla Firefox 1.x:
- Total security advisories: 22
- Status: 95 percent fully patched; 5 percent partially patched
- Criticality: 68 percent Moderately (or less); 27
percent Highly; 5 percent Extremely
http://secunia.com/product/4227/

Microsoft Internet Explorer 6:
- Total security advisories: 17
- Status: 41 percent unpatched; 47 percent fully patched; 6 percent workaround; 6 percent partially patched.
- Criticality: 54 percent Moderately (or less); 35 percent Highly; 12 percent Extremely.
http://secunia.com/product/11/

Bonus fact: One of the unpatched IE flaws is a "highly critical" buffer overflow issue -- from August, 2003.