Your overcomplicating the setup. The easiest way would be to use a diffrent output (There is a PS2 VGA Adaptor that includes 2 channel audio RCA jacks) and connect video directly to your moniter. And as long as your system can handle RCA jacks for audio (theres plently of converters to convert RCA to the mini inputs a PC uses), you can avoid using a capture card.
For my PS3, I use HDMI to my moniter, and Optical to my sound system. No capture device required.