How to get full display resolution for some games on notebook PresarioR3000 series with ATI mobility Radeon 9000 IGP graphic chip

hello all,

My daughter and me are disappointed by the display resolution for games
like Happyland Adventures (http://www.freelunchdesign.com/) or Santa
Klaus in trouble (http://www.cdvspiel.de/ostern/index.htm). Funny and
nice free games for kids.
But on our Compaq Presario R3117EA, Happyland resolution is 640x480 and
Santa Klaus resolution is 800x600.
Default R3000EA series resolution is 1280x800 !
These games are running on our old Presario 14XL355 with 1024x768
resolution !
At the beginning, Santa Kaus has run in full screen resolution so I
know it's possible.
Compaq r3117EA is equipped with only 256 Mo DDR Ram, and 64 Mo is shared
with the graphic chip. Since Windows XP is installed on this PC, I've
decided to decrease shared memory from 64 to 32 from bios menu.
After a while, we saw that Santa Klaus was running with 800x600
resolution. Then I have upgraded the PC with 512 Mo DDR ram more, and
increase shared memory between system and graphic ship from 32 to 64 Mo.
But Santa Klaus was still running with 800x600 resolution.
So to get a better resolution, I've tried :
- to set default display resolution to 1024x768,
- to suppress and re-install ATI driver (partial and full operation),
- to suppress and re-install Santa Kaus game, Happyland, Doom, ...
- to set bios configuration to default values. Surprise ! The factory
set for shared memory is 128 Mo !
- I checked forums on internet,
- I checked windows register base,
- I checked all parameters in ATI configuration panel,
All that without any result !
Doom and Happyland are still running with 640x480 display resolution
which is a quarter of the screen side !

Can anybody help us ? Any idea ? Did I miss something ?

Thanks for your help,

Soib