DeltaMac
Tech
I have iMovie. All Macs that have shipped for the last (4?) years also have iMovie. If you have your original restore disks, and less than 3 years old, then you also have iMovie. iMovie comes with Jaguar 10.2.x, and Panther 10.3.x, but not Tiger 10.4.x. You can install the one you have and update it through the Software updater. If you are asking for a version 4 or later, those also are installed on newer Macs, and are a paid update with the iLife software.
ElDiabloConCaca
U.S.D.A. Prime
iMovie is only available on the Macintosh platform. There is no iMovie for Windows.
(Macintosh, because there is no windows version 
.)