Hey i want to know out of the following which is the best combination or ram..
512+512
512+1gb
1gb.
its pc4200 ddr2 533mhz ram.
use a matched pair of sticks to run your memory dual channel, eg 512+512
if you plan to upgrade get a 1gb now and then add in another 1gb stick later
btw is this for pc or a laptop ?
It is good to have 512 + 512 provided you put them in the right slots.
i.e.
Slot 0 of channel A
Slot 0 of channel B
Just read about this in the morning. But if i am wrong, please somebody correct me. 
If you are planning for an upgrade like bottle said, plug in 1Gb in slot 0 of Channel A.
But make sure they both have the same speed to get the best performance.