If you can, get more power than you need to delay the 'obsolescence factor'. Line up access to good service, either with the store that sold the equipment, or with a good technician. If you can afford it, get the largest monitor and smallest dot pitch you can afford. You will stay awake longer, and save your eyes. Depending on the type of work involved you may need a printer.
Laser printers cost more up front, but are faster, render better quality and cost less in the end.
On the other hand, inkjets cost less up front, do great colour, and some models render great black and white quality. You can beat the high cost inkjet cartridges by refilling them yourself. If all you need is a word processor, fine. However, if you need more, an office suite combines several programs. Both include web browsers.