Trying to use binary replication - from tutorial

Hello,
I am somewhat new with postgresql trying to find a good method of
replication for my company.
I am running through the tutorials on binary replication for postgresql
9.1. Both servers are virtual box Ubuntu 10.10 on a laptop.

I ran this rsync -av --exclude pg_xlog --exclude postgresql.conf
/var/lib/postgresql/9.1/main/* postgres:<ip-address of
standby>:/var/lib/postgresql/9.1/main/

The standby server then will not restart. It says it is missing
pg_xlog/0000000000 ... files

I ran the rsync again not excluding the pg_xlog. This time both servers
restart but there doesn't seem to be any replication occurring.

I am curious why this is going on - why it didn't work excluding the
pg_xlog. Was there something wrong with my syntax? Is there something I am
missing not found in the tutorial?
I will appreciate any help, advice.

Thank you,

Evan