Question about VACUUM

Hello all,

I inherited a 8.1.x database of size 200GB. This database hasn't been
maintained much (autovac is enabled though).

I been trying to VACUUM this db for the past few days for a couple of
hours/day. The server runs 24x7 so continuous maintenance is not possible
(this is the last resort).

My questions are,

> Is it possible to estimate how long VACUUM on a table might take?

> The table size is growing as "VACUUM" is being performed. I assume I need
reindex after VACUUM is complete.

> I run VACUUM from psql and I Ctrl-C it to turn it off is this acceptable?

> maintenance_work_mem is at 64MB and shared_buffers at 2GB. Should I
dedicate more memory to maintenance_work_mem to speedup VACUUM?

The server is a Intel Xeon 3.0GHz with 4GB RAM and RAID-5 (Yes I know).

Thanks in advance,
Steve