Ok i have a toshiba A205 4707 it has a 1028mb or memory stock i want to get another stick to put in the second slot. i found alot of 1028 memory on tiger direct an found that kind i need ddr2 but i wants wonder beside every memory he say like667Hz or 533 hz dose it make a difference when im buyin memory or is it ok just as long as i have to match memory sizes?