Ok , if you want the Sound card to not Get installed , you need to turn it off in the Bios like GX1_man said...
But you can use it for input in BF2 if you really want to, it will be a Drag on you system tho, but as long as its on in the Bios it will be a Drag on you system any way
if you want to turn it Off, If you have an "Award" Bios (the one Ive had on my last 3 computers)
just hit Del to enter Bios
Find Integrated peripherals
Find On Board Sound RealTeck AC97 (Mostlikley...)
Change Enabled to Disabled
Hit F10, Press Y , and hit enter
If you want to use the Second sound Card as an input Device, Go to Control Panel, Sounds and Audio Devices , open the Recording Tab , and Change the Input Device to The Onboard Sound Card. (i have done this once Before it did work , but using 2 sound cards can Kill your system)