ClearType and IE 7
Internet Explorer 7, which will be pushed to users in an almost forced manner shortly, will use ClearType by default. ClearType essentially uses a clever technique called sub-pixel rendering to provide clearer text at low resolutions. Like anti-aliasing, another technology to achieve similar results, it can make things look blurry but on the whole it looks okay.
One of the side effects is that vertical lines get a coloured “halo” which can be a little off putting. On the whole you get used to it, but after leaving it on for a while I noticed something: the problem is essentially a side effect of using “high readability” fonts like Verdana. Verdana was designed to be readable at small sizes and such has a lot of straight lines (since curves either look dodgy or need anti-aliasing at small sizes). These straight lines (specifically vertical ones) are the ones that have the most pronounced halos. Use fancy curvy fonts (even if it’s just a little) and the problem is greatly diminished.