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installed on a Windows XP it is a bit outdated though and I personally feel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.