Hi Cath,
Your laptop is compatible with The Sims 3 if you play it at low graphics settings.
Here is what to do to make it work
Perform ALL steps below In Order...
1: Make Windows fully up-to-date via Microsoft Update.
You did not say if you had XP, Vista or 7. So I will just assume you have Windows 7.
Here is a tutorial I made on how to update your Windows 7 PC in case you need it
http://www.cleartechinfo.com/How-To-Update-Windows-7-Microsoft-Windows-Update2: After all the updates are installed, Restart your PC
3: Update your ATI Mobility Radeon 4250 graphics card. Below are links to the latest updates…
Vista/Windows 7 32-bit:
http://support.amd.com/us/gpudownload/windows/Pages/radeonmob_win7-32.aspxVista/Windows 7 64-bit:
http://support.amd.com/us/gpudownload/windows/Pages/radeonmob_win7-64.aspx4: Restart your PC for the new graphics card drivers to fully take effect
5: Disable/Exit all Anti-Virus, Security, Firewall programs you have running on your PC (they have been known to interfere with some game errors)
6: Open up Sims 3 but DO NOT play it yet
7: Go into the Sims 3 settings, specifically Graphics Settings
8: While in Graphics settings, Move All the Slider adjustment bars to the LEFT
UNcheck All boxes
Set the Graphics Resolution to the Lowest Possible it will allow you to set it to
9: Save the Settings and exit
10: Place the laptop on a desk, table or flat surface. Preferably in an area with a cool temperature. Make sure none of the laptop vents are covered, they need to breath freely.
The reason for this is that when the laptop is on your lap it sometimes overheats when it is running highly demanding things like video editing and especially game playing. Also when it is on your lap they vents may be covered up a bit.
11: Plug the A/C adapter into the laptop.
When the laptop is running on batteries it will automatically slow down your processor and sometimes graphics card to save battery life. This will make a compatible laptop so slow it will become incompatible.
12: Play The Sims 3
How does it run now?