The Problem:
Word for the Mac takes forever and a day to start up.
The Solution:
Check that you haven't got two copies of the application on your Mac. One possibility is that you've installed Word or Office twice, but what's more likely is that you've tried to create an alias to Word by 
+Option-dragging and the Option key wasn't pressed far enough to register, so the Word executable has been copied instead.
If you have two copies of Word, delete one of them. Word should then start at normal speed. If your Mac is old, or sick, that normal speed may still be glacial, but at least you won't be contributing to the problem.
You can save yourself a lot of time and grief by keeping Mac OS X and Word (or Office) updated to the latest versions available. Run Software Update (Apple » Software Update) regularly to check for Mac OS X patches and updates. To check for updates to Word 2004, choose Help » Check for Updates and use Microsoft AutoUpdate. In Word X, choose Help » Downloads and Updates and use the browser-based update mechanism.
Replace Your CarbonLib File
The Problem:
When I start Word X, I get the error message "Shared library error (CarbonLib)." I tried installing the evaluation version of Word 2004 to see if that'd make the error message go away, but it didn't.
The Solution:
The intriguingly named CarbonLib is a Mac OS X system file that's needed for running some applications. This message means that CarbonLib is damaged, which can prevent you from running Word. Download the latest version from the Apple web site (http://www.apple.com/support/), install it, and then run Word again.