Welcome to the wonderfull world of digital. I have a DRebel, and I would suggest getting an extra batter, or two. I carry 3 with me at all times. Two in the battery grip, and I can shoot all day, with an extra one in my pack. I wouldn't risk going on a nice trip like you are planning without at leas one backup. Get 2 extras if you can afford it. I shoot fine jpegs and can get about 150 shots on a 512 card, 300 or so on a 1 GB card. I haven't tried shooting much in RAW yet, the camera says I can shoot 69 RAW files on my 512 card, 139 on the 1GB card. So use your judgement as far as what you think you will need, based on your shooting style, then double it . Better to have too much memory, than to run out on the trip of a lifetime. If you have a laptop, take it with you so you can download your images when you get a card full.

One other thing to consider is, the larger the card, the more you have to loose. A 1GB card with 300 photos on it, is a lot to loose if something should happen to the card...