I would drop them asap, pointing them to microsoft.com in the meantime.
As just a suggestion, courts look favourably (ahem, I believe) in freedom of expression sites. A site about how weak Microsoft passwords are might keep you in the clear... Do not put any advertising on it and voila, a paypalsucks.com type of site... I dont know what the courts might think of you selling a site and dn like that, but I wouldnt like to find out.
Thank the parking companies for not taking them and putting TM infringements all over the place.