Need help with scroll window

[Rasoul Hajikhani <rhajikhani exchange office etoys com>]

I have a table with 30 columns and I have a scrolled window that allows me
to view all the rows. the problem is on opening the window, the table is
very small and I have to resize my main window to make the table larger.
Is there any way that I can give a defualt size value (wxh) to a table.
Please help this thing is driving me crazy...
-Rasoul