MS Office always slower on Mac?
Since the Windows version pre-loads some of the apps at boot time, here's how to do a comparison. 


Start with your Mac turned off.
Press the power button and start your timer.
Wait for the Mac to boot, then open Word. When Word is open, stop your timer.
Then repeat the test for a Windows PC, starting with the PC turned off.


Also note that Office 2004 was written for PowerPC chips, but you're running it on an Intel Mac. That slows things down because Intel Macs have to translate all that PowerPC code into Intel code. If you upgrade to Office 2008 or 2011, you'll have an Intel version of Office for Mac, and it should run faster.