@Alchaeon Wait, You can make white bkgs transparent in SAI?
And @Timber, There is a way you can do that. :) Select the image and then under the selection o the left handbar, there are two shapes, one selected and one not. Select the one that isn't. You'll now have a transparent bkg. That's for XP and below; for Windows 7 I haven't figured it out yet. Sorry. :P Google it?