Simple Accumulating Number Loop?

A friend of mine has created this simple accumulating
loop query for MS SQL 2k5 Express Edition. I am
trying to reproduce the same results with PostgreSQL
8.1, but am not able to find much useful help on how
to properly set up a variable of both int and char.
The PostgreSQL documentation is great if you have an
idea of what you are doing, but I'm still really new
to PostgreSQL. If someone can just point out some
hints or clarifications as to wether to use the SET
command or the psql \set command. Below is the query
in question.

Many thanx to any that can help.

-Ubence

declare @variableint int
declare @desc char (50)
set @variableint = 0
create table counter (countid int , description
varchar(50))
while @variableint < 500
begin
set @variableint = @variableint + 1
set @desc = 'The Counter is Now' +' '+ cast
(@variableint as char(50))
insert into counter values (@variableint,@desc)
end
select * from counter