You want a wireless print server. (Like this) It's a small box that the USB connector from the printer plugs into, and which appears as a shared printer on your network.

If they're both on the same subnet (depends how your wireless is setup), you just need to enable printer sharing (Windows instructions, Mac instructions). You don't need any new hardware and it's not a particularly challenging feat these days.

I do this with my printer and my desktop and my laptop. I'm on a Mac, though. The thing I did that got it to work was that I figured out that my printer had its own IP address that was different than the desktop it's hooked up to. Then I found it on the network with my laptop. I didn't have to buy any separate parts.

Here's the thing about having a device (printer, in this case) dangling off the side of a computer that shares the device out to the network: It Sucks.

According to Murphy's Law, the PC will invariably be switched off, asleep, crashed, upgraded to Linux, unplugged so the margarita machine can use the outlet, or your buddy wants to print from his Mac laptop, or otherwise be in a state where you can't just click "Print" and you get hardcopy without getting your ass up off the couch. (Fun Fact: In Windows, if you move a USB printer to a different USB jack, windows will see it as a different printer, and Voila! Your shared printer is now broken.)

With the standalone box, for $80 plus a few cents on your monthly utility bill, It Just Works. I set one of these print servers up for my parents maybe six years ago - last xmas when I was home, it was still there - serving a new printer to new a pair of PCs; they hadn't needed to call me to ask how to change out everything. Sweet, sweet sweetness.

When folks ask me about computer stuff and the question includes words like "clueless", I tend to steer them towards the set-it-and-forget-it option, especially if the cost is less than my hourly rate to talk them through fixing it a second time when the bailing wire & bubblegum stop working.

Excellent solution, Triode - I have been wondering if there was such a beast, as we have exactly that problem - our only printer is plugged into my PC, so it has to be turned on for anyone in the house to print. No big deal, but it gets old after a while for all of the reasons you noted.