How are mod chips different from each other? (newbie question)

Hi, I'm new here!
I'm totally new to this, so please be understanding if this sounds dumb :)

I wanna buy an Xbox 360 as soon as it's out in November (never had a gaming console since PSX), and I understand it will need mod chips just like old Xbox does. When I go and choose what chip to buy, what should I take into consideration? What are the things that one chip can do (or can do better) while another chip can't do (or can do worse)?

I'm sorry for being a n00b, but I can't seem to understand why aren't all chips equally useful.

I will appreciate help very much! Even a link that explains this would be enough, because I can't seem to find one.

Thanks,
Fishos

As the only chip i ever had was an x2.2 lite i couldnt tell you.

as for the xbox360 modchip... no one has any idea of the old chip developers are even going to be interested in this system... anyway, dont expect to see a functional chip for the xbox360 for at least a good 6 months (and seeing as how microsoft is discussing the security mabey even longer)

check www.xbox-scene.com for more information on that note.