Careful Microsoft
After the Blaster/Sassar and all the 2002-ish mass virus breakouts, Trustworthy Computing was a bold move headed up by Bill Gates (Remember reading the letter he wrote to announce it with a sigh or relief, after clearing up a bunch of mess those worms caused)
Yes, it may have partly been PR, but the perception is that it led to Windows XP SP2, which was a leap forward in security, with a built in firewall on by default, Pop up blockers, and extra security in IE6. Other products followed, and while they weren't perfect, the code quality seemed to improve dramatically, along with things like patch Tuesday, and a central area to keep up to date on security.
So, OK, Microsoft - close the department, but don't you dare stop doing the work and ethos they promoted, or they'll be hell to pay.