extending a wireless network up a block of flats

[Slinky]

Im looking to replace an existing wired network, which has a network switch on each floor to provide access to the adsl router in the basement, with a wireless network.
My plan is to simply replace the switches on each floor with a wireless access point of some description.

However thats where I fall flat, what equipment do i need to do the job.

 

[Slinky]

thanks for the replies, the reason for going wireless is partially age of equipment and the difficulty involved in wireing new installations.
I had seen some reference to wireless repeaters so im glad i was thinkking along the same lines.
I'll let you know how it goes