Computer hardware should be upgraded or replaced every three to four years. Hardware is a bargain, quality is up and prices are down.
Hardware prices are very competitive. You can easily check prices online at Dell or Gateway. However you need a lot more than just the hardware you also need the service to set it up, install the applications, set up the network, trouble shoot problems and provide service and support.
These value added services vary significantly in cost.
Choose your hardware vendor with the same care you would any professional advisor. Get references. Choose a vendor with dental office experience.