PHP application hosted on a dektop ubuntu(localhost) vs A .NET software installed on Windows

Hi, I need some help and its actually got nothing to do with any coding help. My friend owns a business and has been using a software developed on VB6.0 installed on a Windows XP it is a bit outdated though and I personally feel the company which sold the software has overdone the sales, coz I personally feel its way too crappy. Now that my buddy has asked me to get a software developed for him if I would like to. I am thinking that since I am more of a web app guy than the traditional software developer, would it make any sense to develop an application which would run on localhost on a Ubuntu Desktop ? I am not sure if it does sound like an appropriate alternative or does it sound like someone trying to avoid the process of an installable software ? Also if it can be done, then Ideally what are the things that I should be taking care off ? and was really keen to know how many of you have come across situations like these and offered solutions like this if atall Thanks, Vinay Kannan.