two quick questions about the MP ram

[phuong]

i bought the basic 2.66GHz MP with 4GB ram option (4x1GB)
now i want to add 4GB more

question is,
1.does it have to be the same, identical ram from Apple, or can i buy them from crucial? (they say these rams must come in pair or something..)
2.at crucial, they have 2x1GB and 2x2GB options. which one is better? (i mean, for the same 4GB capacity, but there are more "bandwidth" with the 4x1GB than the 2x2GB aren't there? so 4x1GB might be faster than 2x2GB)

 

[Scarlet Fever]

1.does it have to be the same, identical ram from Apple, or can i buy them from crucial? (they say these rams must come in pair or something..)

No, but they must be exactly the specs that Apple provide. Crucial seem to have a good reputation around here.

2.at crucial, they have 2x1GB and 2x2GB options. which one is better? (i mean, for the same 4GB capacity, but there are more "bandwidth" with the 4x1GB than the 2x2GB aren't there? so 4x1GB might be faster than 2x2GB)

Not sure, but i believe 4*1GB will perform better than 2*2GB.