Sandisk, but i wonder if it isnt the size of the memory causing the problems.
Remember back in the day motherboards were limited to a certin size of memory? anything over what it was rated for caused problems? I wonder when the S2 was designed 2gig memory cards were even available to test?
What if you used 4 512 cards? if a memory problem happens it wont ruin the data on all the cards. They are so small and so easy to change, just curious.
Before you tried to format it did it recognize the card as a 2GB card? I doubt if the problem is with the S2 recognizing a 2GB card. The only card that I ever put in my S2 was a 2GB TRanscend 150x and I shot at least a couple of thousand pics before it was formated. And the only reason I formatted it was because an aquaintance said that he had once lost some pics and someone in a photo store suggested that he format the card in the camera but it was not a canon. So I just did it for GP, either way no problem with the 2GB card and the same card also works fine in my S3. It should tell you it has a capacity of 1.8GB. What does the camera recognize it as? I am inclined to believe the issue is with the card.
I typically shoot only super pics at a recent private event that covered three days I shot 1024 pics. From which I used nearly 700 pics in a compilation. I have shot 500 pics in a day on several occasions. Basically it's all relative to how and what your using the camera for as to what size disk or disks will meet your needs. Considering my needs it would be prudent to have another 2GB card dedicated to video only. I actually would have prefered that a 4GB card would have worked, I like the option of not having to swap cards. It decreases the points of vulnerability.
The camera sees the card as 1.9GBs. I'm on the same boat as XaiLo 2GB is the minimum I want in the camera. I can fill a 2GB up fast. I always shoot on the highest quality settings so I just ordered the 2GB TRanscend 150x that XaiLo recomended.