Hi Ivan,
It's the old cliche, "you don't get out for nowt", as the say in lancashire..the most succesful way I have found, is to trim the jpeg 'fly on the wall', this way you can reduce it's file size exactly for the quality of picture you require.i.e. quality/ file size trade-off,
Try
their jpeg optimiser, great little program, shareware...
Or depending on the jpeg, try and reproduce it with vector graphics, which are scalable, without degrading the graphic.
If it is a oneoff, import the jpg, then reduce it's alpha (easier to trace over),then trace over the top, using flash's vector graphics, can turn out ok, depending on the jpg used..