For the past year or so, I've repeatedly been trying to bring up what I see as a huge, gaping hole in any project which uses Microsoft products for an ICT4Development rollout - computer viruses. Windows XP, when connected to the Internet sans protection, lasts as few as four minutes before becoming infected, and rarely more than a day. Multiply that by hundreds of thousands of OLPC XOs running Windows (with no mention of anti-virus software to date), and you have a nightmare scenario pretty rapidly.
The much-debated VitalWave TCO paper we discussed at the World Bank, which argued that the higher cost of Linux administrators balanced out licensing costs for discounted Microsoft and anti-virus software, even admitted the significant costs of purchasing and maintaining a subscription to anti-virus tools
If Microsoft wants to continue to capture the developing world market, this is going to be a barrier. They can drop their own licensing costs for the XP Starter Edition (which at this point is zero cost to them) down, and hand out older Office software; but the initial and subscription costs for anti-virus software are not (directly) under MS's control. Regardless, having anti-virus protection directly impacts the functionality of the device - if installed, A-V can slow a less powerful computer down to a crawl during a scan and at startup, but the consequences of not having it can render the system absolutely useless.
So it comes as little surprise that Microsoft has announced a free anti-virus software for XP and Vista that targets lower-powered systems (cough, like the OLPC?) to address both these problems and lower the cost barrier for adopting MS: