actually there are 2 easier ways to do this, well one, firstly
string $myWin = `window -width 100 -height 250 -sizeable 1 coolWindow`;
This saves u editing the window.
Secondly create this window and drag it to a size you want. Now in the script editor enter:
window -q -wh $myWin;
This will spit out the size that u have manually resized the window to, just enter these into the first bit of code. (We could have used the -wh flag in the first example, -wh 100 250)