Get whichever you find works better with your cam. I've got both old (8X?) Sandisk and new (30X) Transcend. Only feel the diff when I d/l the images in my CF reader... or when I use them on my friend's S1 Pro. There is really little diff on my CP4500 or my A70.
Since you are asking about 1Gb, I will suppose that the Sandisk is an Ultra series one. Beyond that, both brands are good and rugged. And well supported in Sg.
