Another request for shader source! :D
Also, I wouldn't worry about integrated graphics chips that much anymore. Hell, my $500AU Eee laptop can do Pixel Shader 2.0!
That said, though, an alpha-tested fallback shouldn't be too hard to do. If you're worried about aliasing, just draw the character several times with a low opacity and jitter the positions slightly, but when it comes to older systems (Older than 5 years, for sure), I generally just think "Make it work, don't worry about making it pretty".