I have an old laptop computer. It's 200MHz, 2gb hard drive, 128mb RAM. I want to load one of the small Linux distros. The only special application I need is a SIP VoIP client. Anyone have an idea about which of the micro-distros would be best?

You could try Damn Small Linux, it's only one I really know of that is a small distro as such - but don't know if it would do what you want it to as I've never used it. You could use any distro in essence, just have to make sure that you don't install Gnome or KDE because they would use all the space on your system and not work very well since you've only got 128MB of ram. Therefore, xfce or another window manager would be all you'd need plus the sip app.

That's indeed the fastest (installed on hard disk of course) and lightest distribution I ever installed on my nomade laptop (see spec in signature). Nowadays, I'm happy with Debian and IceWM (although I find Debian slow to boot).
Not quite; 2.6-kernel-based distributions won't install on too-old hardware. For example, on my nomade laptop, Mandrake 9.1 was the last Mdk/Mdv I was able to install (and it ran slow). You can always try and use Live CDs to test.

I recommend IceWM or ROX as the desktop.

Yves.

Though that's nothing to do with the 2.6 kernel itself, it's just the way the distro is configured and the way the distro configures the kernel. Large initrd/initramfs, kernel compilation options, extra services, don't help.

If the processor is i686 or greater, (So Pentium II or Pentium Pro), you could run Arch Linux on it easily.

You could try installing bum or sysv-rc-conf and disable any un-needed services it might help make Debian faster.

Thanks to all those who replied. I did some reading over at http://distrowatch.com/ and found three small distros that seem as if they will do nicely. The three are Damn Small, Puppy, and TinyMe. I have not tried any of them yet. Puppy looks like the one I'll try first because of the way it runs from RAM. I am not sure if the others can easily be made to runs from RAM, but the descriptions for Puppy includes this; "Puppy boots into a 64MB ramdisk, and that's it, the whole caboodle runs in RAM". If that works well I won't need the hard disk.