General advice to booting diskless client needed

[Rudolf Bahr <box_1@quasi.de>]

Hello,
I'm new to the list. Therefore greetings to all.

I needed some general advice to booting a diskless little box
(AMD Geode GX-533, 256 MB RAM, no internal HD, no floppy, no CD,
 4 x USB, VGA, Ethernet).

I'd like to have 2 boot-choices:
1. Booting over LAN using a USB-HD
2. Booting over LAN using only the available 256 MB RAM.

BTW, does exist a way for booting from an external 
boot-server without any help by a LAN boot server?
(An external boot-server beeing available, my little boot client beeing in
 my LAN with a gateway to internet)

Up to now I experimented with a boot server in my LAN using PXE
trying to use a USB-HD:
a. Boot-client connecting to boot-server using DHCP (getting IP-Address, etc.) 
   worked fine (with ISC DHCP).
b. Using TFTP to get boot-choices and kernels worked fine 
   (with tftpd-hpa, filename "pxelinux.0").
c. In /tftpboot on the boot-server was untared netboot.tar.gz, date 05-mar-2005, 
   from debian/dists/sarge/main-installer-i386/current/images/netboot.
   results: c1. linux26 and expert26 both ended with:
                "<0> Kernel panic: Attempted to kill init!"
            c2. linux and expert didn't recognize the USB-HD. 
                Therefore finish at that point.

   I didn't add any boot parameters in addition to the existing ones.

I'm new to the topic, therefore I bought the little box just to play with
and to learn about that.
Any hint could help me.

Greetings and thanks,
Rudolf