I got a question I hope i meet the the requirements for Leopard because I don't plan to upgrade this year. But sometime next year I will be doing that so I can take the full advantage of 10.5.
My 12" PB:
1.5ghz PPC G4
768mb ram(for now, soon 1.25gb)
60gb hd along with a 320 HDD
GeForce FX Go5200
VRAM (Total): 64 MB
Vendor: nVIDIA (0x10de)
Should handle Leopard easily. A bit light on the graphics side but so are many of the new Intel machines.
The difference between 10.6 and 10.5 will not be major.
And you know this how?