wal logs in pg_xlog

I am using postgres 8.0.3, and wanted to use Point In Time Recovery enable.
could any one tell me about how to indentify the current WAL file, also
let me know if there is any fix patteren for WAL log file generations.
documentaion says it will generate ever increasing number starting from
some thing like "0000000100000000000000000". but I have observed
different behaviour. I would also want to know, how does it archive
files. for example we have log file 000002, now when archiving  will
it  start new  file  as  000003 or  will it  archive  000002  as
000003  and  lastest will  be  same  as  000002.

- Nasir