add chrome to your PATH.
[windows-logo-flag-key]-R [Pause/break] Advanced, Environment variables, User Variables, PATH, Edit.
hit the End key to go to the end of the string and type in a semicolon (

followed by the path to your google chrome executable.
you can get the path to your google chrome executable by start, command prompt, type in
cd "\program files"
dir *gimp* /s/b/ad
if it has a bin directory, use that. right click on the window, pick mark. then select the text of the path you want from c: on to the end of the line, and hit [Enter].
it would look something like C:\Program Files\GIMP-2.0 except it would have the word Chrome in it probably, maybe google.
paste that into the PATH after what's in there already.
click OK. click OK.
if you know the executable's filename, say it's chrome.exe, you can now do
[windows-logo-flag-key]R chrome http://www.microsoft.com [Enter]
or simply
[windows-logo-flag-key]R chrome microsoft.com [Enter]