I've an 2.6.21.5 kernel, hmm and I know that we have already 2.6.24.x
how can I be every week up to date ?

pre thanx carlitoco

download the latest kernel from www.kernel.org and follow the compile guide in the sticky thread.

All slackware kernels are vanilla by default so any updating has to be done by yourself and since there is no patching from slackware you do not have to worry about waiting for the patched kernel releases

Hi,
Why?

What do you need the newest kernel for?

This is mostly true. The kernel in Slackware 12.1, for instance, included a small security patch - linux-2.6.24.5-CVE-2008-1375-patch.

So, it more correct to say that Slackware kernels are vanilla with the exception of security patches. The vanilla kernels integrate the security patches in later versions, while Slackware allows you to use the same version with just the security patches.

Therefore, to answer the OP's questions, you should really only need to "update" your kernel if you need new features (typically drivers).

Speaking of kernels and patches, did you ever install the kernel patches for Slackware 12? These were added after the initial release unlike the one I linked to above.

You can grab the source from kernel.org every week, compile it, and install it.

Soon you'll find out why this is not a good idea if you want a stable system. (Hint: not every kernel release is stable even tho they say it is) Or maybe you want to test the kernel ? If so, you'd want the unstable kernel.