What is the minimum capacity a memory card should have for the Canon T2i?

Either get 2 8GB (class 6 or higher) cards or an 8 GB and a 4 GB (as a backup in case your primary card fails or fills up... carry the spare card and a spare, charged battery pack with you when you go out shooting - to ensure nothing fails at a critical moment).

Happy shooting!

I shoot a 7D which generates nearly identical files to the Rebel T2i. If you aren't shooting RAW, an 8GB card is more than enough even if you are shooting at maximum resolution. A 4GB card will hold several hundred photos if you are only shooting JPG/JPEG. I almost never use my cameras for video but, when shooting JPG/JPEGs, I can easily get over 1000 images on a single 8GB card at maximum resolution. Video takes up considerably more room and you'll see far more limitations with respect to recording time for video.

The size of the video clips is limited by the file system of the card (FAT32) which means the biggest file you can have is 4GB or about 12 minutes of continuous recording at the highest resolution per clip. If you have a 32GB card, that's a theoritical maximum of eight, 12-minute clips. The reality is you won't get quite that much video because you lose some flash capacity to formatting.

i have a 16gb card just incase.. it was only like $30 at b&h.. and i take 1 picture when i take the shot not just rapid shooting.. and i go out for a day and use at least 10 gigs but i am also shooting in raw but i really dont think it makes a difference

8GB will be good for your needs..... good luck!