I have a 4 Gb A-Data card I use with my XTi ... I also have a Lexar 4 Gb Professional 133X, and a couple of Ultra II 4 GB, which i use in the Xti or the 40D ...
The A-Data card is no doubt the slowest to transfer files to the computer, using the same card reader as the other two. In the 40D, my non quantitative feeling is that the Lexar is the quickest, with the Ultra II and the A-Data trailing, and too close to call. In the XTi there is no difference in any of them, or so it seems to me.
All this said, if I didn't have the other two to compare it to, I would probably think the A-Data is fine.
Maxdave
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