Here are instructions in Office 2003 for installing Microsoft Equation 3.0.
If you have Office 2000, I can't imagine that it would be too much different.
I got these instructions from Help in Word.
"If you originally installed Microsoft Office from a network file server or from a shared folder, you must install Equation Editor from that location. If you installed Office from a CD-ROM, you must install Equation Editor from the disc.
Quit all programs.
Do one of the following:
If you run Microsoft Windows 2000, double-click the Add/Remove Programs icon in Control Panel.
If you run Microsoft Windows XP, click Add or Remove Programs in Control Panel.
In the Currently installed programs box, click the listing for Microsoft Office or Microsoft Word, depending on whether you installed Word as part of Office or as an individual program, and then click Change.
On the Maintenance Mode Options screen, click Add or Remove Features, and then click Next.
If a Custom Setup screen appears, select the Choose advanced customization of applications check box, and then click Next.
In the list of features to install, click the expand indicator (+) next to Office Tools.
Click the arrow next to Equation Editor, and then click Run from My Computer.
Click Update.
Restart Word."
That should get you going.
Let us know how you like it.