Please, don't fall into the temptation of adding too many so called "features".
E.g: If we must "view source" on the notepad (as in IE) instead of a very nice colored syntax windows (as in NN), that's ok, but don't add too many lines of code just for the latter.
This is an example of where customization becomes wonderful. Instead of a hardcoded link to any editor for viewing source, allow the user to speficy the editor. Perhaps the default could be notepad, since almost every Win32 box has it, but let the user specify their favorite syntax highlighting reformatting editor.
Personally -- as the oddball supporting teaching labs -- I'd also put in a vote for having a NONE setting that disables viewing the source. Think of it as a setting for kiosks, elementary school labs and libraries where you want as little as possible to confuse the users.
I'd have to agree with Albert, that customization of the "view source" would be great. Opera allows this, which means I can use TextPad which handles syntax colouring.