network design

I have responsible person to setup a network to my office.We have 10 offices at different location.Now bombay is central office.Others three is main branch office & remaining are smaill branch office.Now we wants to connect all the office to each others for permanent connection or dial on demand.We also wants that all the office is also connect to internet also.So Please give me what i need to implement such kind of scenario.Also You suggest me hardware requirement with good performance.

Thanks