A Few Problems please help me

I went onto the microsoft.com website and did a check for updates, it came back with some updates to download which i did. One of them didn't download properly and this was Office XP service pack 3 so i just ignored this and carried on using the computer. Since then whenever i turn on my computer i get an error message come up:-

error loading w0016f20.dll

Also i keep getting the updates coming up to say that i need to update service pack 3 but when i click on it to update it doesn't update fully.

I tried to do a re-store but for some reason it will not allow me to restore at any point at all - Why??

Lastly, i cannot gain access to Excel either, it comes up with a message saying it is trying to install Microsoft Office XP Professional with Front Page and because it cannot find a particular file which is called PROPLUS.MSI it will not install.

Please can someone help me....

PROPLUS.msi is on the office cd
Be sure the proper Office cd is in the cdrom tray and then try to do the office sp3 update