We have a wireless setup at home. We have a desktop system at the cable router location (in our breakfast nook / office), and two laptops with USB Wireless G adapters. I have an 'ad-hoc' mode setup, WEP secured - as long as we don't venture outside our range with the laptops (theoretic range for Wireless-G is 200-300 feet, realistic range is more like 100-150 feet).
In my setup we don't need a wireless router - it could save you buckaroos too. Also, at one time, our local Home Depot had USB wireless adapters mistakenly priced at $19.97 each - the low end for USB wireless adapters is usually around $40. I did let them know they had it mispriced when I bought my first one (for work, I'm the IT guy) - but it took that store manager 3 weeks to change the price so I stocked up on what I needed.
If it's not a 'must do now' kind of project, I'd wait until the Wireless N standard come out - Wireless N will have much better signal range and speed than Wireless G. There are some 'pre-N' products out right now, but I'm waiting until Wireless-N is ratified and standardized before purchasing. That's part of the existing problem with Wireless-G - some microwave ovens and cordless phones operation interferes with Wireless-G frequencies.