Blue Tit or Great Tit?

Today we're having lots of snow again. Somehow my trusty Kodak camera now shows a grey spot on every light picture (this can be clearly seen on my previous blip, look below the right lower sail of the mill), so I drove to a store to take a look at the Canon EOS 500d. It seems to be a great camera, so I ordered it.

When driving back, the roads were covered with lots of snow and driving was quite dangerous as evidenced by a truck that had slid of the road. On the way back I stopped at my parents-in-law. There I took this picture from the safety of their kitchen. I made it home safely and won't be going out anymore today because the forecast says we're going to have more snow...

I don't know much about birds but I think this is either a Blue Tit or a Great Tit...