|I have XP Home too, and no SPs.|
Some time back, I had the same problem.
I think I solved problem by enlarging each window manually to fit the screen, without doing the "Restore up" or "Restore down"
button at the top right corner of the window.
Then after that, when I opened a program window, the window would be OK.
Do you know how to enlarge a window manually ???
RESIZING WINDOW ----
My Solution ------
With mouse pointer on the Title Bar (top bar on the window),
hold down left mouse button,
now move top left corner of window TO the top left of screen.
Now place mouse pointer at the bottom right corner of the window,
until you see a Double Arrow,
then hold left mouse button,
then drag the window's corner to the lower right side of the screen.
NOW all windows of that program should open the same,
without having to click Maximize.
Do not rely on resizing one program window to fix windows of other programs