<<< I would like to be able to print from the laptop wirelessly without having the PC switched on >>>
In that case, you need one of:
(a) A printer that supports "Network Printing", i.e. connects directly by ethernet to a wired network - the "wireless router".
(b) A network "Print Server" that plugs into a wired network with a USB port to connect a conventional USB printer.
(c) A Wireless Router/ADSL Modem with built-in Print server providing a USB printer port.
Note that with option (b), Print Servers with a Parallel Printer Port are more common than those with a USB Port.
The Netgear DG834G range will perform the router function for you - internet access and file sharing - but you still need a Print Server unless (a) above applies.