Plug-In to Internet Explorer / Firefox

We need an extension to Firefox 1.5 and Internet Explorer 6 (and if possible also 7). When the user selects an arbitrary text with the mouse or text cursor in the browser and press mouse-right-click, one of the options should be "search XYZ for ". The XYZ will be our web service and is of course the actual content the user has marked, with a truncation to something like the first 100 characters. When the user selects this action, a new window shall open in the browser and the URL will be static except for the which will be passed as an URL-encoded parameter. The truncation to something like 100 characters also applies here. It's a plus if these add-ons are bundled in an msi-install-file. Either all in one, or one per each browser. The plug-ins are intended for public spread, and cannot contain copyright protected code. When buying this functionality, we also buy a copy of the source code. This means we aquire the comercial and legal right to modify and sell the code and derivates of the code with no restrictions. We see no issues if the developer would like to have equal rights to the code.