The Nokia 5800 has a very large high res screen which is compatible with many touchscreen Java games in full-screen mode, for example Cooking Mama works on the 5800 in full screen. Unfortunately the default setting for many Java games and applications (including Cooking Mama) seems to have the on-screen "virtual keypad" switched on automatically, which makes the game or app shrink into half-screen mode. However, there is an easy solution to this problem which should let touch-compatible Java software use the 5800's entire screen. See below for a quick step-by-step guide...
How to make Java games and apps work in full screen mode on the Nokia 5800 XpressMusic
1. On the 5800's main menu screen, select "Settings".
2. Select "Application Manager".
3. Select "Installed Applications".
4. Click once on the app or game you want to run in full screen mode.
5. Select "Options".
6. Select "Suite Settings".
7. Select "On-Screen Keyboard".
8. Select "Off".
9. Select "OK".
10. Press back until you leave the settings manager, or press the red button to close it down.
The game or app will now automatically use full-screen mode from now on. If you need to get the virtual keypad back, just repeat the above process and choose a different option from the "On-Screen Keyboard" section.
You can also use this method to stop the phone constantly asking if it's okay for a Java app or game to connect to the internet, just select the relevant options from "Suite Settings".