Is it wireless

Hello,
We are looking for a new computer for our front office. The server is in a different room, and there are 2 work stations and 2 laptops. We have a wireless network, and all computers print to a big all-in-one machine leased from an office solutions company. The workstation we are replacing is the one our receptionist uses. We have found several refurbished models, and everything seems compatible. The problem is, they all come with RJ-45 integrated 10/100 LAN. Does this mean they can connect to our network wirelessly, or do they require a wired connection? It doesn't say either way. Please let me know your best opinion. One model is an HP, the others are IBM's. They are refurbished, off-lease models from what I assume are companies - all come with updated Windows XP Professional, which is more than fine for our practice management software.
Thanks!