Phoenix, just search for "kernel" or even "linux". Then have a look through the list.
According to your post #10 you have kernel 2.6.18-5-amd64
So you need:
Note, I'm not 100% sure about the -amd64 on the kernel-headers, I never used amd64, so just see what is listed for you.
@dwhitney: Perhaps (like myself) he doesn't have any need to update his distro (I'm still on 2.6.15 and very happy)!