Only when you're talking about games -- not for anything else.
I believe Photoshop does utilise some memory from the card, andl this is what Adobe recommend, and to be honest in my experience this is true, when scrolling through large documents with large files in etc.
"For optimum performance in Photoshop, use a video card with more than 128 MG of RAM. "
The most important thing about it though is the screen, as the 24 is such a large monitor, this memory can only help, especially if you are intending on keeping it a while.