problem with Qt designer for Qt 4.5

Hi,
just installed Qt 4.5 (with mingw),started designer but,when I select any of the options like 'Widget without buttons' or any of the others,I get a very small frame which I can't seem to enlarge.I have attached a screenshot.Any idea what i need to do to get it to enlarge?I tried selecting the sizes like 320x240 and 640x .....the size doesn't increase.

Thanks in advance for any suggestions.

Hi,
update.....
I tried reinstalling Qt but it still shows the same results.I tried changing the size by varying width and height but to no avail.The strange thing is ,if I try to preview the form,I can see the whole of it...but in designer it looks like the top half of the form is cut off and only a small segment at the bottom is visible.
Any ideas on why it's happening or what you think I should do to get Designer working properly would be appreciated.
I am trying to install on Windows xp SP1.

Hi,
the designer issue has been resolved.I was using a vista theme on my Windows XP,so,a member in the qt-mailing list told me to remove the vista theme and try on the normal Windows Xp look.It worked.Designer's working properly now.
Got a simple question about Qt creator-----
I plan to download Qt creator,so,do I have to run any command for the Qt creator package I download(and install) and the Qt package which I have installed to work properly with each other or,do I just have to download Qt creator and install it and everything else will work properly.

Thank you.