Optimal database table optimization method

Hello,

I have a database table that is growing too big (few hundred million rows)
that needs to be optimized, but before I get into partitioning it, I thought
I'd ask about suggestions.

Here is the usage:

0 . Table contains about 10 columns of length about 20 bytes each.

1.

INSERTS are performed at a rate of hundreds of times per second.
2.

SELECT statements are performed based on column 'a' (where a='xxxx' ) a
few times per hour.
3.

DELETE statements are performed based on a DATE column. (delete where
date older than 1 year) usually once per day.
4.

The key requirement is to speed up INSERT and SELECT statements, and be able
to keep history data of 1 year back without locking the whole table down
while deleting.

I would guess that I must have two indexes, one for column 'a', and the
other for the date field. or is it possible to optimize both ?

Will there be a necessary trade-off between speed on select and speed of
delete?

Is partitioning the only solution ? What are good strategies for
partitioning such table?

I'm using a PostgreSQL 8.4 database.

Best Regards,

Roger Tannous.