when you are on the pages with the UdpRaw files, there are options above the source listing as follows:
embed / history / annotate / raw
click 'raw' to get the source file without line numbers or other annotation.
OK, I had another stab at this - I will say I find that website layout very confusing - only this time I grabbed the zip package of Arduino_Osc. As I hoped the library files were all there 
When I tried to compile this time it complained that it couldn't find the string files. Copying them from 'String' into 'Ethernet' cured that problem, although I suspect that's the wrong thing to do.
It now complied completely so I happily fired up the RS232 monitor reset the arduino board and got two memory messages - looking good, although I was slightly suspicious that the memory after starting the server appeared to be the same as before.
However, boldly going where no man has gone before, I fired up the laptop, with it previously restored to the default configuration for using DHCP to get it's IP.
No dice 
and the serial report was that there was a memory leak of 4294967043 bytes - I'd be seriously impressed if the atmega had that amount of memory!
I originally got the DHCP server sketch from here, but I can't remember where, and can't seem to find the thread again
Can anyone suggest something I can run on the laptop (Linux) that will send/receive UDP packets so that I can at least find out if that part is working correctly?
I have not tried it but there is a UDP library for processing here: http://www.ubaa.net/shared/processing/udp/
Processing is here : http://processing.org/
Thanks for your reply.
I've actually been able to track down the correct thread on here it is:-
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1239258729/45
I've made more detailed comments there so won't clutter up this thread unnecessarily.
Hello,
same problems here with arduino-0019.
The most important message seems to be:
/usr/lib/gcc/avr/4.3.2/../../../../avr/include/stdlib.h:504: Fehler: vorherige Deklaration »long int random()« hier
This is forced from 'extern "C" { ... }' at begin of the UdpRaw.cpp file. Simple delete this two lines will make things better.
But the UdpRaw-Package is like the Udp-Package in the Ethernet directory.
The other messages will forced from missing "types.h". Comment this out and fix the last two errors:
Sn_MR_UDP --> SnMR::UDP
getSn_RX_RSR --> W5100.getRXReceivedSize
Compiling now ok 8-), but no guaranties for proper work.
Good luck, Thomas.
Can somebody please confirm whether this fix works? I've got it compiled but the packets don't fly at all. Using IDE 0021.
Thanks.
You might like to look at my last post here:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1273689407
for a working Udp program