Can't speak to the ZX, but I have had a SB Audigy 2 Platinum EX for a while now and it has never failed to impress me.
I have the lastest drivers via the auto-update (european server).
I use it with Cubase SX and Sound Forge 6 with zero problems.
And, just to top it all off, I played Far Cry and Doom 3 through the SB + Creative 6700 speakers without a hiccup. (when using it for music production I re-route the connections to a set of professional monitors)
Summary, if there is anything that is doubtful about the ZX range (though I am not aware of any) then see if you can find the EX somewhere (bound to be cheaper now) and with confidence I can say you will have excellent results.
BTW, as the EX has the separate module for all I/O, I have tested all sorts of connections RCA - S/PDIF - Phono and MIDI IN and OUT with success first time attempted.
I cannot speak too highly of the card and the results at either the software or the hardware level. I cannot be the only person that has had similar experiences or Creative would be out of business pretty quickly in this "dog eat dog" market.
And NO...I do not have ANY affiliation with the company, nor it's subsidiaries.
Just a happy user.