I use PowerPoint 2000. My experience has been that EPS files can be
inserted, but for some reason which I haven't had time to investigate much,
colors tend to get altered. I've achieved the best results by copying the
EPS graphic in the graphics application (i.e., Illustrator) and pasting it
as an Enhanced Metafile into PowerPoint using Paste Special. This converts
the graphic to line segments, so I generally enlarge the graphic before
copying it, then shrink it down after pasting so that the segments are less
noticeable.
This can also be done by first exporting the graphic to a Windows Metafile
(.WMF) format, then inserting the picture from the resulting file.
The results look great in print- however, they don't always look that great
on screen. One workaround I've found is this: once the graphic is in
PowerPoint, cut it and paste it back in as a .PNG file using Paste Special.
This tends to eliminate the jagged edges when viewing the slide show.