igloo

...office on my computer? i want to install the ms office on the cd, which has the full non-trial version of powerpoint and publisher, and on my computer, my powerpoint and publisher are trial versions which i can't use.
do i have to delete my ms office on my pc first then install everything on the cd? because i tried installing ms office with my version of ms office(with trial stuff) still on the computer, and it couldn't. said it had error, had to roll back, did it 3 times still doesn't work
and if i delete ms office and can't install the one on the cd, what do i do? if i can't get ms office back on computer and i don't have anything (no word, excel, etc)