Need Expert Advice on Registries please !!!

Hello,

I'm looking for several registry keys:
1. the date on which the Operating System was installed
2. the processor of the machine
3. the MAC address
4. the RAM

I KNOW that this information is available by running some windows utilities,
like sysinfo, which collect it on my behalf. However, I need to know WHERE
(i.e. in which file or registries) these are *stored*.

PS: I am not sure whether there ARE registry keys which store such
information. Does there exist some kind of a "documentation" which details
all the possible registry keys and their meanings ?

thanks ahead for any feedback,

--Fluffy