You want a USB or PCI wifi adaptor. About £20-£30, and should self-install in a few minutes. You could almost certainly spec. it in the new machine.
Examples:
USB adaptors
PCI adaptors
The advantage of the USB adaptors is that they can be used on other PCs very quickly, though I should say that two out of three USB adaptors supplies by Netgear that I bought two years ago have been replaced under warranty. You do also have to have the adaptor protruding from the case (they are about 3" long) or attached to the USB port with a cable.