I want uprade my RAM to 4 GB, but i don't know what brand to buy(Kingston? PQI? Apacer?...?). Now in my Mac's RAM slot there is 1GB DDR2 SDRAM 667Mhz.........must i buy the same type (i mean DDR2 SDRAM 667Mhz) or i can buy 800Mhz or 1333Mhz, will they work? Advice me please. Thanks.