Hi, I also own a SD1 and I did install the 4.0c OS....in comparation of the 3.0x...well, to start, you have an option in the 4.0 OS..to have newer and (even Finer sounds to my ears)...also an embelish and improved dinamic alocation(a little better), the user styles also easier to load. Also you can download the new styles too. In a nutshell, I am very happy with mine.

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mdorantes