Creating a Chat and File Transfer Webservice similar to Gtalk

[madthomas]

I want to create a Standalone web service like Gtalk that allows user to chat and share files.
The Web service will run as a Standalone application and not in a Browser.
The Application must support minimum 10 users and maximum 25 users and should be able to run on LAN.
1. Which Language should I use .net or php?
2. How to make the web service as Standalone .exe file (like Gtalk)?
3. Any other information that can help me to get started

[Miko001]

One option to rap an HTML5 chat page in an exe file.
You can use a 3rd party chat service (java script oriented).
Try rumbletalk chat or cboxi chat