MD-
Not sure why you believe the Audigy 2's don't support 24 bit...any links?
From what I found regarding it's limitations on the 24-bit issue is that it can’t record in 24-bit using ASIO drivers (which reduces latency)...got that from a
Maximum PC Review which is an excellent source of accurate information IMO...
If you choose the M-Audio card, it does have excellent sound quality, some say better than the audigy...but it lacks its own onboard processor and uses your main proc...bringing down performance...this card is usually recommended for musicians...certainly not gamers.