Hey, everyone! My first Mac purchased is my macbook that i bought last year in may, its been working perfectly thus far and i was thinking perhaps i should buy leopard and install it. Now my question is: Do i need to do a complete reformat of my HDD or will installing leopard just overwrite my existing tiger and work just like the normal software updates i have been downloading ? Does anyone want to explain how i would have to go about putting leopard on my macbook? and if its possible to do so without reformating. Thanks!