The later versions of MS Office removed Photo Editor, 2003 I think. But if you've got 2000 installed you can probably still get it, Like matty said.
I don't think it's installed by default so you can check by going to:
Control Panel -> Add/Remove Programs -> Microsoft Office -> Change -> Add or Remove Features -> Advanced Install/Customization... Photo Editor will be under Office Tools.
The directions aren't word perfect but I'm sure you'll get there