good morning macrumors.
i'm looking to buy a sdhc card exclusively for my t1i's video function.
some background
[i currently have a 4gb sdhc from Digital Film with the words "ultra HIGH speed" written on it. and "class 6" but when every time i shoot in 720p the video stops after about 5 mins. (i think sensor heat is after 12 mins) and when i shoot in 1080, it stops in about 10 seconds. The bar with the round edge boxes fills up and BUSY shows up on the lower left.]
so which card should i buy? i'll most likely be buying it at fry's. i know class 6 is the fastest now (not including class 10 cuz i can't find it anywhere) but is there any difference in speed between class 6 cards? and looking for 16-32GB

i'm looking to buy a sdhc card exclusively for my t1i's video function.
some background
[i currently have a 4gb sdhc from Digital Film with the words "ultra HIGH speed" written on it. and "class 6" but when every time i shoot in 720p the video stops after about 5 mins. (i think sensor heat is after 12 mins) and when i shoot in 1080, it stops in about 10 seconds. The bar with the round edge boxes fills up and BUSY shows up on the lower left.]
so which card should i buy? i'll most likely be buying it at fry's. i know class 6 is the fastest now (not including class 10 cuz i can't find it anywhere) but is there any difference in speed between class 6 cards? and looking for 16-32GB