10.5 has considerably higher graphical requirements than 10.3, which only does the basics. As 10.5 places greater reliance on the GPU - in this case a lowly 6200 (which is a PC-flashed card is 64-bit), running Core Image, it will seem a little slower. However, in theory it places less load on the CPU which even things about, the the 6200 while a little sluggish with some desktop operations is quite decent for most things.

JB