Any computer geniuses out there?

I just bought the latest expansion pack for my favorite game, Medieval: Total War II and I get these error messages when I try to install Medi II Kingdoms:

"This update cannot be continued," This 1.03.000 update cannot be applied
to the 1.00.000 version of the game," and "Failed to apply updates to Medieval
II: Total War. Aborting installation."

Anyone reading this know how to fix it?

Update

Nerd that I am, I figured it out myself. I 1st had to delete my old version of Medieval II, then reload it (also had to delete the folder and files that were left after the deletion). Then I downloaded patches 1.1 and 1.2 (1.2 took over 3 hours to download, and I have a cable modem!). Once those things are done, the game loaded perfectly.