Sorry this can't be adjusted, there's no language string or parameter in place to do so. It would require directly editing the core code which is not supported and can not advise on.
One alternative is to use the non-breaking HTML character for space to space the title away from the colon on each and every field until they're even. You can find such character at the following link.
www.ascii.cl/htmlcodes.htm
Example as follows.
Username(space)(space)(space)(space):
Name(space)(space)(space)(space)(space):
Post edited by: krileon, at: 2010/04/07 15:42