I'm going skiing for the first time and don't know what to bring vs. what to rent!?

Help! I'm going skiing for the first time on January 8, 2010 and have no clue what I should buy vs. what I should borrow from friends vs. what I should rent. We are going to Park City, UT and we're from the east coast. I'm not a huge fan of snow, so I don't know how much to invest in this sport since it's the first time I'm going and I may hate it. Everyone says I need ski pants/bib, but is that something I can generally rent at the resort or is it better to buy my own? Also, what do you wear under your coat and ski pants when you're on the mountain? Jeans? Thermal underwear? Pajamas? I just have no clue because I've never gone. I have a jacket that I got from Lands End, so that will work (it's good for up to -10 degrees, so I'm set there). What else should I know about skiing in general in addition to specific things I need.

Thanks in advance!