Small home office phone system?

Hi my setup in the house so far is 2 telephone lines 1 for calls 1 for fax and a 4mb broadband , i will be starting my own buisness and was looking to get a phone system like big companies have

"press 1 to sale press 2 to complain etc."

i would like the ability to monitor my calls on the desktop and see what department the call is coming to and accept basicly a switch board on my computer

im not too bothered about a desktop one this would cool although i would settle for a phone with flashing lites for diffrent departments , if possible ?

ive also heard about VOIP phone systems using my internet would it be alot more reliable to use a phone line instead of internet , incase of brakedowns?

Thanks for anyone that can help

Gary.