Hi, I have a slackware 11.0 installed, i'am a newbie. I don't understand which is the difference among i386, i486, i686 and no arch. On my control center I read that
I have a i686 machine, but I have installed packages where is written i486, i386 and even noarch.What does it mean?

Bye Bye.

i386 is a third-generation processor (80386)
i486 is a fourth-generation processor (80486)
i586 is a fifth-generation processor (Pentium)
i686 is a sixth-generation processor (Pentium Pro or higher)
i786 is a seventh-generation processor (Itanium; first generation of 64-bit processors)

Here is a link that will let you review various processor types:
Microprocessor Types

Generally speaking, anything that is designed for a processor that is less than or equal to yours, should be compatible.

"noarch" means that the package is architecture independent and it really shouldn't matter what your system specs are for it to install and run properly.

Welcome to Linux :-)