32 bit or 64 bit for web server

We had a confusion on how to go about the webserver, which 30 concurrent users are assumed to be using at a time. The application we are developing has a desktop component and webcomponent. So we decided to go with 32 bit OS for development and 64 bit OS for webserver. Webserver requires more RAM and also better configuration. I shall update this session on what all problems we will face during the course of project in this thread !!