m'kay. The difference between GD and gaming is the 3D aspect. Unless he's designing the games...he can go with lower 'polygons' or depth of detail in the 3D. The more memory his card has..the better his card will perform with photoshop and illustrator (more photoshop because illustrator works with math, curves and angles more than heavy photos). Fast on MB memory is VERY useful too... he can go cheap on the vid card if he's got decent onboard ram on the MB (and it's cheaper overall). YThe GForce 6600 or anyhting above it will kick ass in Photoshop. DVD playback and some mid-episode vid in games will require a faster CPU (on MOBO) or on the card (Again...it's cheaper to upgrade your processor on teh Mobo than on the vidcard.)
Your friend can save cash by finding vidcards without TV-out, s-video, dual monitor support...it's fringe-toys and not really necessary.