This probably has more to do with your operating system than it does Office. But, since you are running Office XP, I can only assume you are on least Windows2000. The bad news here is AutoCAD 14 probably isn't going to run at all on anything greater than WindowsNT 4.0. But you may get lucky -- if you can, disable any and all but the most necessary applications and then try your install. At a bare minimum, you will have to disable the anti-virus software.
HTH
Todd