The SoundBlaster Live does much more than add a few effects. In addition to 3D Surround, EAX, midi, etc, it provides quite a few ports for line-in, line out, microphone, midi, and a few others. I agree with DodgeTigger. Yes, you can do a lot of this in software, but at a significant penalty. The point here is that it is supposed to take a load off the main cpu, like graphics cards. If I were to (supposing the Mac OS, either 9 or X, provided the features my Radeon 8500 & SB Live have) put that load on my G4, the penalty would be quite severe. In my view, the reasons cards such as these exist are multifold: First, I don't think most people want their main cpu to bear the brunt of the load of processing those types of signals. Second, until we see the day when G5s arrive with 200-400 mhz bus speeds, 2ghz cpus, etc., if you want those features included with such cards, you really do need the extra hardware.
Also, as I mentioned earlier, it has sound-in. For the life of me, I can't figure out why Apple called my G4 a 'digital audio' model, and yet took away any sort of sound input hardware. Yes, the audio has gone from analog to digital, but the name's a bit misleading. For those of you who simply want audio-in and nothing else, the iMic is your best bet at an affordable price ..