Yes you will notice a difference with this sound card. It outputs sound at 24bit instead of the pultary 16bit that the others output. However the main benefits of the newer cards besides stunning quality is the compatiblity for EAX 4 which will basically mean a very realistic game experience. However if you want this card to reach it's full potential why not get some 7.1 speakers - Creative do a very nice set for about £100
PC Spec: AMD Athlon XP 2000+ running at 1.25ghz, ECS K7S5A Motherboard, 768MB SDRAM PC133, Sparkle nVidia Riva TNT2 M64 32MB AGP Graphics Card, Creative Sound Blaster Audigy 2 6.1, Windows Me