Ok, Everybody keeps saying that Postgresql is free...
So I contacted my webhost and their respons was they have to pay a
license fee.
But because they use PLESK as a service I think they are refering to a
fee PLESK charges them
for the use combination PLESK - POSTGRESQL
Probably.
Although in my humble opinion, proposing postgres 7.3 in 2006 is a bit
disrespectful to the considerable work that has been done by the postgres
team since that release.
If you don't find a host to your liking, and you have a large website, as
you say, consider a dedicated server. Prices are quite accessible now, you
can install the latest version of Postgres. Going from 7.3 to 8.1, and
having your own server with all its resources dedicated to running your
site, will probably enhance your performance. Consider lighttpd which is a
speed demon and uses very little resources.