VACUUM ANALYSE...

Hello,
I have a database running with postgres 7.2.3-1.
Some tables gets feed with about 200000 records a day. A cronjob does
"VACUUM ANALYSE" at night.
This takes about an hour. In this time the performance gets real bad. After
a short period the client (Apache running on another machine) hits the
MAX_CONNECTION value and refuses any incoming connections. Systemload goes
up to 20..
Is there any option to get a vacuum-analyse less priority or should i
upgrade to the latest version?
excerpt form the postgresql.conf:

shared_buffers =70000
max_fsm_relations = 100
max_fsm_pages = 2000
sort_mem = 128
vacuum_mem = 8192

Thank you

Thilo Hille