Which is it? Does the printer have wireless abilities of its own or doesn't it? You start off saying it does, but then say it needs to be connected via an ethernet cable.
If it has wireless capabilities built in, just put it somewhere it can get a wireless signal. If it doesn't, what exactly is stopping you from running a cable up to the router? You can go to a Menards or Fleet Farm type store and find a box of Cat5 ethernet cable, probably some RJ-45 ends, and a crimper. Then a little bit of detective work with Google to figure out the proper way to wire an ethernet cable, and you can have a cable of significant length for pretty cheap. You can also cut it exactly to length, so if you only need 22.5ft of cable, that's what you can cut.
If for some reason you really don't want to run a cable to the router, then you can get a wireless ethernet bridge device. Shouldn't conflict with the router at all. Think of it like a USB based wireless card, only instead of USB it connects via ethernet.
Hi - we have a few laptops in our home running Windows Vista - we use a wi-fi system in the house - our internet connection is wireless. For Xmas I received an HP Printer with wireless capability, but it needs to be plugged into the ethernet of the router. Unfortunately, the best reception for our router thru-out the house was in our upstairs attic - far away from the central office where I would prefer the printer. All the wires for the connection run through the attic to the router in this location and cannot be changed. I was told I might need a wireless bridge with an ethernet port, but was also told that there might be a "control issue" between the two routers. Is there a simple way to add an extra router or something else downstairs to plug the printer into so we could utilize the wireless feature of the printer, or should I just have everyone plug in to print? Thanks for your help!