most audigys won't record 24bit simulaneously with playback. but that won't cause latency - just errors if that's the case.
are you using WDM or ASIO driver mode? latency is caused by the latency buffers.
if you're using WDM, then go to OPTIONS>AUDIO and move the latency slider to the FAST side (this might cause clicking/popping/dropout)
if you're using ASIO, then click on the ASIO button and that will open your Soundblaster software. from there you'll have to find the parameters to change the hardware buffers. increasing them increases latency, decreasing them decreases latency.