I was going to buy a 2.66Ghz/2GB/X1900 but I now have the opportunity for a great deal on a 3Ghz/4GB/X1900. Only difference is it is used....I have never purchased a used computer before and am a little hesitant. Any drawbacks to doing so? It is 3-4 months old so, I assume the 1 year warranty would transfer and it would be eligible for Applecare. Appreciate any thoughts on this.