how to truncate/purge the pg_xlog directory?

Hi

As far as I understand pg_xlog is the transaction log i.e. the WAL.

I have a pg 8.2 which has consumed about 113MB in pg_xlog/, while the
cluster is virtually empty. There are a couple of tables in the postgres
schema, but they contain no data at the moment. My disk is filling up and
I want to purge directories that are larger than need to be.
I performed a VACUUM FULL, because I thought that would help, but it did not.
I searched the net and the forums here and found only one post about
tuning the wal parameters to control the pg_xlog directory size, but when
looking at the documentation for that I found nothing that could be used
for that

Also the base/ directory is 268MB big and still not many tables, is ti
possible to purge that directory as well?.

I would appreciate some help on what to do.

regards

thomas