I bought one of these sound cards, and spent a fruitless few minutes trying to get it to work with Linux's soundblaster driver, before realizing that (despite the name) it's not a soundblaster at all.
How to tell if you have one: type the command "lspci". If your output includes a line like the following:
00:0d.0 Multimedia audio controller: Ensoniq 5880 AudioPCI (rev 02)
then you have one of these devices. In my experience, the soundblaster driver will not work.
You can get more verbose output with "lspci -v". The relevant part of the output looks like this on my system:
00:0d.0 Multimedia audio controller: Ensoniq 5880 AudioPCI (rev 02)
Subsystem: Ensoniq Creative Sound Blaster AudioPCI128
Flags: bus master, slow devsel, latency 32, IRQ 11
I/O ports at e000
What to do: the driver for these cards is actually the es1371 driver ("CONFIG_SOUND_ES1371" in Linux 2.2.18). Use that, and everything should work.
This web page exists merely to produce a hit in search engines, so that anyone else who has this hardware has a better chance of discovering how to get it to work.