[gocard]

It's a serif font, which makes it noisier in my opinion. It's also a relatively thin font, making it more difficult to read.

[gocard]

Compare the fonts on this page. Courier gets muddied when it's bolded, and feels a tad thin when not, in my opinion:

http://hivelogic.com/articles/top-10-programming-fonts

The last 3 fonts listed on the page are really strong for programming.

[leokun]

The l has a serif, but other characters do not.

[gocard]

On Courier New? Mmmm, a lot of the characters have serifs.