QPapillon,
You can't do it natively in PPT, nor in Word for that matter. You could fake
it though. Draw an rounded rectangle from the AutoShapes and place it on top
of your table. Select your table and apply a no border line to all the
lines. That should make them disappear. Then reapply the inside border lines
only. Now adjust your rounded rectangle to accomodate the inner lines.
To jazz-up your table you could apply a suitable background using the fill
options, a combination of two colors or even a picture as background. Click
on the arrow next to the paintbucket on your drawing toolbar, choose fill
effects, choose picture tab...
