Hi Piers,
With OSS emulation (either mode) RAT should run ok on this card. However as far as I'm aware (correct me if I'm wrong Doug) the AG-RAT-CVS (mentioned by Douglas) uses an ALSA driver which has trouble with the SBLive's usual ALSA mixer interface (it isn't currently handled properly the AG-RAT-CVS). There's a number of cards that also use the same ALSA kernel module: emu10k1
Cheers, Doug