if you are choose between EG and CG, i think the difference is not so big. depands on if you want to overclock it to extreme and buy separate cooler.

how about socketT? do you want to consider it, too? the advantage of 775 is the new chipset, support pci-e, hi-def audio, 4 sata. a lot of the feture you may not use it now.. but maybe useful in a year. for example, faster graphic card next year may be available only on pci-e. or you want more than 2 harddrive on s-ata.

the motherboard and cpu price should be quite similier to 478 version. but if you have already have a fast agp card and wan to use it. then 478 motherboard is better.