setting display resolution

Hello,
I'm trying to set the display resolution of Windows XP running in Parallels Desktop on my Macbook Pro to 1280x960.
However, as the Macbook LCD only supports resolutions up to 1440x900, I'm not able to set the desired resolution in fullscreen mode.
I'm therefore trying to set the resolution in OS-window mode.
This works for like 1 second, but then the XP screen is automatically resized to the actual visible window.
I want Windows XP to keep the resolution set (like 1280x960) and Parallels to have scrollbars instead of automatically resize the XP screen resolution, but I cannot find any way to set this, even though I remember to have seen Parallels just behaving like that.
Any help appreciated!

 

Please install Parallels Tools and enable custom screen resolution

 

I have parallels tools installed...
but, where do i enable the custom screen resolution?

 

Parallels Desktop for Mac user guide from http://www.parallels.com/en/download/file/doc/Parallels_Desktop_for_Mac_User_Guide.pdf page 172

 

I'm using the lastest version of Parallels Desktop for Mac with MS Windows Fundamentals for Legacy PCs.
Usually Guest OS is displayed on external monitor. Today I pivoted my 1280X1024 monitor and tried full screen mode but it was not same what I wanted to be.
Then I remember that there was a custom resolution options in Parallels Desktop for Mac 3 and searched it.
But I can't.
How do I use custom resolution such as 1024X1280?

 

There is no such feature now, custom resolution
If you want custom resolution, please stop Parallels Coherence service from Start -Run - type services.msc