SERVICE PACKS and UPDATES

Just wondering if someone could clarify,

I was having some issues with my FSX after I tried the DX10 Beta stuff i guess its called, for XP. Well, i lost my water rooster tails in my sim and it was showing black lines here and there in the sim while flying. Well, I was advised to go ahead and remove FSX and reload it. Well Ive removed it, havent reinstalled just yet, however, my question...If I have already installed my SP1 and 2 which included the DIRECT X10 update , and my SDK update, do i need to uninstall those before I reinstall FSX, or can i rest assure that they are in my system and will automatically go into where they need to go...or do i just redue everthing? and for SDK update...it will only let me DL it if i put in the first disc of FSX...could someone shed some light on this and tell me what to expect or exactly what they mean...sorry guys...a nube here to all the doc moving and dls and knowing exactly how to do it...

Thanks!!