Setting 100 character guide in visual studio

I was searching a way to set a vertical line guide after 100 characters in visual studio. This functionality is given in most of the source editors. I could not find a direct way to do it in visual studio 2005. Finally Ruwan Janapriya gave a "hack" way. You can set registry setting in [HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\8.0\Text Editor] and set a string value of "Guides"="RGB(0,0,0) 100", then it will show a vertical line after 100 characters with black colour.