Early skiers strapped long pieces of wood to their winter boots and pushed themselves around with sticks. No more. There's no good substitute for modern skis or snowboards, boots, bindings, and poles (for skiers). And, when you rent them, these marvels of high-performance engineering can come cheap.
Rent or buy? Until you become a dedicated, regular skier or snowboarder, it's best to rent equipment. Buying is an unwise investment if you don't ski or board enough to justify the cost.
Rental equipment has a reputation for being outdated and ill maintained, but many ski shops have some of the latest equipment in their rental stock, with a range of prices reflecting the equipment's relative quality. Rentals are almost always adequate for the needs of beginners. Once you master the basics, you'll start to get a feel for performance differences, and this may be your cue to consider buying.
Where to rent? Prices tend to be somewhat lower if you rent in your hometown rather than on the mountain. Additionally, renting at home can save time on ski days and let you be a little choosier about your gear--though you will have to schlep everything to the mountain and back. Alternatively, you can wait until you get there, then rent at a local ski shop for ease of transport. Then, if something breaks or isn't quite right, you can have it fixed right in town or at the bottom of the slope. This may be reason enough to choose this option.
Clothing. You may already own much of the clothing you'll need for skiing or snowboarding, including a parka, t-shirts, flannel shirts, sweaters or fleece, long underwear, warm but not bulky socks, and a ski hat or earmuffs. Warm, water-resistant ski pants and gloves can be borrowed or rented at some ski and outdoor shops if you don't want to buy just yet (get them before you go).