microsoft messenger for sp1 windows xp

I ahve a problem of being stuck with version the old version 5.0. When I download 6.0 that can be used with sp1; it boots up to the login page and when I log in; it says to update yes or no and when I click no; it does not let me go on and when I click yes; it of course trys to force me to down load the newest version and trys to force me to upgrade to sp2 which sucks if you like the old media player 9 and the old movie maker that both do more than any newwer version that takes those rights away from you to do those tasks. How do i get past that block to upgrade? I looked in all the boxes of 5.0 version and cannot find a box that you can uncheck a option not to :automaticaly update.

 

What's wrong with installing SP2?