Major CPU/HD use

I'm using CoLinux (colinux.org) and PostgreSQL, every 10-20 minutes my
HD and CPU go to massive use for about 5 minutes and I am very curious
about who's causing it (I do know for sure it is coming from Linux and
not Windows).

I am no Linux expert and I quite baffled about how to get such
information in the cosole (tried 'ps' but it didn't seem to have such
information).

So the main questions:

1) Does your PostgreSQL behave the same? Or is it only my setup?
2) Is it possible that I turned autovacuum on by mistake or something
like that and it just vacuums my DB every few minutes?
3) How can I check, in console, which process in linux uses the CPU
(the way I can in Windows Task Manager).

Thanks.

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