/proc/stat on amd64 explanation?

[Michal Hajek <hajek1@karlov.mff.cuni.cz>]

Hello people :)

in /proc/stat on my Amd64 (AMD Athlon(tm) 64 Processor 3000+) I have:

mymashine:~$ cat /proc/stat
cpu  936448 76085819 423225 42441 2878 2250 345302 0
cpu0 936448 76085819 423225 42441 2878 2250 345302 0
intr 813723457 778502009 2 0 0 0 1 0 1 0 0 1 1 3504227 0 30670 0
23184496 0 3 6639698 186484 386065 1289799 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0
ctxt 303922756
btime 1131876576
processes 2132201
procs_running 4
procs_blocked 0

While trying to understand these numbers, I read in the man proc:

/proc/stat
        kernel/system  statistics. Varies with architecture. Common
        entries include:

        cpu  3357 0 4313 1362393

               The number of jiffies (1/100ths of  a
               second)  that  the system  spent  in user
               mode, user mode with low priority (nice),
               system mode, and the idle task,
               respectively.  The last value should be 100
               times the second entry in the uptime
               pseudo-file.

        .....
<cut here>

I am mainly interested in the "cpu ..." line, since it (AFAIK) should
contain some valuable information about how my procesor is being used :)
Though I am curious about the other lines too :)

So what is than the actual meaning of the numbers at my system? 
Why there are 8 numbers instead of only 4 which are explained in man?
Where can I get information about how this "varies with architecture" ?

Thanks in advance and appoligies if this is a too stupid question
and I am overlooking something quite obvious...

Best regards
Michal