The sound card on my system is a SB X-Fi Titanium Fatal1ty Champion Series
http://us.store.creative.com/Creative-Sound-Blaster-XFi-Titanium-Fatal1ty/M/B001BDPLJA.htm
I have it in audio creation mode, and it does support 24 bit, as I have the record option set to record .wav files at 44.1khz, 24 bits. I can also choose 48khz or 96khz rates. The sound card’s software app called Creative Console Launcher includes an ASIO tab, so the card does support at least some ASIO features.
The issue was that Cubase AI 7 did not include the sound card it it’s list of ASIO devices (it only showed the MOXF8), so I was unable to select the sound card as an audio output device. I could not determine how to get a list of sound cards that should work in ASIO mode with Cubase AI 7 from the Steinberg web site.
Regarding Win XP versus Win 7, the Yamaha Steinberg USB driver documentation indicates that it’s Win 7 only.