I've got two cards for my 7D, a Sandisk Ultra CompactFlash card. It's 4 gigs and runs 30mb/sec. I spent about 60 bucks on it I think. I also recently bought a SanDisk Extreme III CompactFlash card that was less than half the price and also rated at 30mb/sec. I noticed when I shoot video on this card it stops every few seconds during playback (about every 5 or 10 seconds) I think because it's not writing fast enough. The first card I listed doesn't do that. I was looking at other cards and found a Lexar Professional UDMA Flash memory card - 16 GB CompactFlash Card for a little over a hundred bucks and the speed rating is not listed as mb/sec, it's listed as 300x. I want to get a bigger card but I want it to be fast enough so it doesn't have problems when I'm shooting video like the Extreme III card above. Is the Lexar card a good card for the 7D? And how fast is 300x?? TYIA.