Network Planning

Hi,
A company has outsource their IT services to our company and I have never involve in any project before but I have been given the opportunity to help in planning and setup a network infrastructure. It has to be cost effective.
Users: 60
Networking devices (Firewall, switches)
Application server
Mail server
Anti-virus solution
Remote Server administration (What software)
Wireless lan solution
Internet services
What kind of vendors those are reliable (sourcing)
Server hardware
Other services
Disaster plan
I hope anyone could share his or her precious experience with me. What kind of products to recommend and ideas