For a small business, your best options are Panasonic, Samsung and NEC. Think about common brands that you know make good electrical products like plasma TV's etc. I really feel people from a non technical background should stay away from voip systems like trixbox and stick with a traditional telephone system that works first time everytime. I own a Panasonic dealership so I am a little biased but I have personaly installed hundreds of phone systems in small businesses and I can say that for the average small business owner, you cannot do better than the Panasonic TDA30 phone system. If you install the voice mail/queuing card, you can have a message to answer calls, play a message and queue them until you can answer. You can have a different message for night/holidays and a personal mailbox for each phone handset.
Panasonic, NEC, LG and samsung phone systems all have these features and all cost about the same amount. For a small phone system with 4 handsets you will pay around $2200 and about $2700 with voice mail.
Panasonic phone systems, small business phone systems