The use of a beowulf. [diversion]

[Animal]

<snip>
>> It is possible to use a beowulf without rewrite the application? Please
>let me know. 
>
>as told here short answer is no.
 <snip>

On that note, I am interested to read about the computer science behind this.  If you could direct me to Books or URLs that tell the different structuring required for a program that makes use of parallel processing.  
I assume it has something to do with handeling threads, can a program do both reasonabley well?

Directions will be highly appreciated, do not go to any trouble.  
Thanks in advance.  
--
Alan Horkan
BA ICT
Trinity College Dublin
Ireland
mailto:horkana@tcd.ie