@JohnAskew: Thanks! So far, we just have purchased some peripherals here, brought the rest with us when we moved here. So, I have never used Dell. I am bit concerned about service, especially regarding the time to solve an issue. Anyway, will for sure have a look at it. NewEgg too, as I used to build my own, although that is a long time ago.
It depends if you want to save money and build a machine yourself or if you want to purchase a machine with an extended 3 year warranty with next day repair or replace.
It depends on how competent your staff are with IT as they will need to retrain to use Windows 8
It depends on whether your business intends to collaborate with other businesses, sending them spreadsheets and word documents, whether you opt for a mac or a pc
it depends on the budget you have available, a few hundred, or tens of thousands of dollars