if my demo doesnt install (like it does at the minute) does that also mean the full game wont install?

i get a problem with direct x installing, ive tried for 2 days, downloading about 10 different files, .dll files, different direct x files, and uninstalled/reinstalled fm10 demo about 5 times.
i never owned fm09 so i dunno if that would have had problems aswell?

every solution seems only to be understood by a computer expert (which im DEFINATELY not) i havent got a clue.

so ive given up with the demo completly, but does that mean if i buy the fullgame, will it not work either? if so i wont bother, and that will be the end of football manager forever for me im afraid.