I had a Canon T1i camera, and it shot 1080 and 720 video fine. When I use the new T2i, the video is very choppy. The 720/60fps, 1080/30fps and 1080/24fps all come out choppy when I play them back on my computer (they look great on the camera). I have a Gateway DX4710-05 desktop with a core-2 quad 2.4 GHz system with 6 GB of ram and added an NVIDIA GeForce 9400 GT 1GB DDR2 video card. I am recording everything on a San Disk Extreme SDHC class 10 card (8 GB). When I used the T1i I was using an SDHC 4 GB class 2 memory card, and the 1080 and 720 video still worked fine. When I played back my T1i movie clips they were smooth when I opened them (they were .MOV movies in Quicktime), but the T2i files are very choppy. Is it that my computer can't handle the higher frames per second of the movies? I didn't think it was THAT big of a difference between the two cameras to make the files run so laggy. Is it the new memory card? Is it a setting on the T2i itself? Someone told me to go from PAL to NTSC (I'm in the U.S.), but it was already set to NTSC so that wasn't it. And here is one interesting thing that I do not understand. When I import the T2i movie files into Sony Vegas 9 and render them as a .WMV files, the file size of the new movies is WAY lower, the quality isn't diminished hardly at all, and the videos run perfectly smooth. So they are choppy when running straight from Quicktime after dragging them to my desktop, but are smooth after being run through Sony Vegas. Why are the original videos so laggy and choppy when I try to run them? Any thoughts?