Microsoft will easily win this one.
1. Bing! Information Design does not currently have a trademark on the name Bing. They claim they have filed for one, but Microsoft will win on the basis of prior use before the trademark was granted--and the trademark might not be granted at all. If they filed for the trademark AFTER Microsoft introduced Bing, it is a slam-dunk for Microsoft.
2. A trademark technically only covers one industry unless it creates confusion in the eyes of the consumer with competing companies. A search engine business is different than a web design business and they do not compete in any way. I don't think they can be confused.
100 companies can use the same name and each can have a Trademark, as long as the name does not create confusion in the market place and the companies are in different industries.
They claim that they have been using the name since 2000. While that may be true, they cannot claim prior use to protect a trademark that they did not own the rights to. IMHO, there is no merit to their claim and it will be dismissed. I think they are just hoping that Microsoft will toss some money at them to make the issue go away.
I am quite surprised that Microsoft did not trademark the name, but I remember back in the late 1990s when Microsoft forgot to renew the registration on the Microsoft.com domain. Doh!
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin