How to set higher screen resolution in Ubuntu guest OS on Virtualbox?

I have Windows 7 as host OS and I installed Ubuntu 10.04 as a guest on Virtual box. Initially the screen resolution in guest screen was restricted to 800 X 600, although I have options of as high as 1280 X 800 in my host (Windows 7).

To change the display of guest Ubuntu OS on Virtualbox to a better screen resolution I installed Guest additions in Ubuntu and steps are explained below:

1. Install Guest Additions: Start guest Ubuntu on Virtualbox and select Devices > Install Guest Additions.

Now the ISO for Guest Additions will be mounted automatically and you should see the CD icon on your desktop (VBOXADDITIONS_3.2.10_66523).If it is not visible just restart Ubuntu.

2. Open the terminal. Applications->Accessories->Terminal. Now go to location where Guest Additions are stored. In my case it is in /media. Now run the appropriate installer. For example: for 32 bit computer and Ubuntu OS commands are shown below:

Provide the administrative password and install will begin.

3. After the installation completes restart the guest Ubuntu OS.

4. Now you can see the available resolution by going into System->Preferences->Monitors.

Go to Machine->Enter Fullscreen Mode and enjoy the higher display resolution.