I have a G4 Mini as well...but even w/ a real GPU in it, it can't even come close to the CD version with intel integrated graphics in terms of video performance...try playing HD trailers on both machines and look at the frame rate...the Intel mini will show the trailer at the proper frame rate with no hiccups, smooth graphics...and all 24 or 29.98 fps...the G4 will be lucky to maintain 12-15 fps.
Even with that handicap, everyone in the family will use my mini instead of my old P4 2 ghz pc w/ an ATI Radeon 9600 w/ 128 mb vram...in most things it will be faster...go figure...
so...PLEASE update the mini w/ C2D, make the price a little more competitive and move on...many of the early adopters are ready for a bump...especially with OS X 10.5 coming!