windows xp sp2 installation problem

recently i had upgraded to win xp. sp1 is intalled using win update.

i had tried to install win xp service pack 2 from a computer magazine cd (not digit, since this month i could not get the same from news stand), when i click intall button,the screen goes blank for a very long time.but in the add remove programmes list win xp sp2 is shown.

however , i am not able to run it or instal it.

since i am not a techie, kindly help me in simple language