A wireless card (or equivalent, they're not all actually cards) is necessary. More and more laptops include them, standard or as an option, internally. Or you can get external ones that plug into your PC card slot or your USB port.

In addition, some services require a subscription. Most offer a variety: pay by the hour (with a one-hour minimum typical), the day (breaks even after typically about two hours) or by the month (breaks even with the daily approach after 3-5 days). You can generally sign up on line and be activated immediately. With some hotel services, especially if it's to be billed to your room rather than to a credit card, you get your ID and password from the front desk. You'll probably have to visit the desk in person to do this, since you get a card where the stuff covering the password has to be scraped off. The desk people could do this for you and read you the number over the phone, but they're not supposed to - privacy and all that.