I have about 16 CF cards now that I number and take with me for important shoots and trips. Most are 4 GB and I have the 5D2 which takes only 123 images in RAW + mJPEG. The 7D will only be a little better. Get yourself a little wallet for CF cards, I have the Think Tank one and it's wonderful for 10 cards, and I bought 4 GB Ultra II's from Costco, they were on sale, and I've never regretted it. I usually have my small laptop and external hard drive to download every so often, but if you don't have anything to download daily, you will be sad you didn't get enough memory right off. Think about it. A 4GB card is 3 rolls of 36 exposure film (for my 5D2). That's not a lot. I only have 1 8GB card, as stated above, eggs in one basket, heaven forbid I lose the card or it fails. During a wedding shoot, that has happened. I put in a card that didn't register in the camera. I was happy I had 7 empty cards still left in my case.