If they have a PowerPC Mac, you could tell them to get
Microsoft PowerPoint Viewer 98. You may need to check some settings when saving your powerpoint presentation (since you’re using version 2003) - perhaps in the save dialog? - to make it readable in pp98. The age issue notwithstanding, there’s also the issue of cross-platform compatibility (as many people know, not all presentations created in PP2003 for Windows always display exactly the same in PP2003 for the Mac and vice versa).
If your friend has an Intel Mac, the above method won’t work. If your presentation doesn’t require being played on a lot of computers, and you both have a lot of bandwidth, you could consider converting it into OpenOffice Impress presentation instead. Just both get OpenOffice at
http://www.openoffice.org (obviously you should get the PC version and your friend the Mac version). (It’s freeware BTW). During installation, just pick the Impress module and omit everything else. Open your powerpoint presentation with OpenOffice Impress. Just go through and make sure all the slides display correctly (most of the time they do, but sometimes it’ll be minor adjustments, like move an arrow a millimeter to the right or to the left or something). Then click file, save as, and make sure it’s saved as an OpenDocument Presentation (extension .odp). Then send your friend that.
The last method involves capturing the presentation into a video (a lot of “promoters” (aka spammers) on the site call it “converting”, but it’s really capture). Use a program like Camtasia (which has a free trial version) or CamStudio (freeware) to record the presentation as you play it back. You can adjust the settings to record audio if needed. Usually the video will be captured in a lossless codec, but if you need to shrink it some, you can convert it using a third party editor (VirtualDub for example - or Camtasia Editor if you’re using Camtasia) using a different codec for higher compression. Then send your friend the end-result video (just be sure they have the correct codec to play back the video).