ShowModalDialog() XP - 2000 Diferencess: Help :-)

Hi All,

I'm writing an hta application that uses showModalDialog method.
My problem is that the size of the dialog changes from win2000 to
win-xp

I tried to draw a graphical ilustration (Please excuse the poor
design;-))

win 2000 win XP
---------------- ---------------------
|################| |############### |
|################| |############### |
|################| |############### |
|#### Table ####| |#### Table #### |
|################| |############### |
|################| |############### |
|################| |############### |
|################| |############### |
---------------- | |
ShowModalDialog | |
--------------------
ShowModalDialog

I have tried using px and em as unit of measure, but with no luck.
I can't set the table to 100% cause it will distort my design!

Code:
window.showModalDialog("THE URL",[ARGS],"dialogHeight:100px
;dialogWidth:200px; scroll:no ; unadorned:yes");

Q1: What is the reason for this differences?
Q2: How can I prevent this from happening?

Best Regards
Shlomi schwartz