Money Format

 hello everyone...,
i have problem in money format...

i have moneytable is containning:
 userid          money
   A            20000,0000
   B            40000,0000
userid type varchar(50)
money type money 
i have store procedure like this:
ALTER PROCEDURE [dbo].[paid]
(
    @userid AS varchar(50),

    @cost AS money,
 @message as int="1"  output
)
AS

begin transaction
declare @money as money

 select @money = money
from moneytable
where userid=@userid

if (@money > @cost)
begin
set @money = @money - @cost
UPDATE moneytable
        SET money = @money
        WHERE userid=@userid
set @message ='1'
end
else
begin
set @message = '2'
end

COMMIT TRANSACTION
 
when i execute this procedure. i insert value to 
userid        A
cost         100,0000
 
it can not decrease, because cost 100,0000 is same with 1000000, why is like that?
i want cost 100,0000 is same with 100.
how can i do that?
thx...