Hi Abbie,
Unfortunately, I think that the CPU of your laptop is not powerful enough to play The Sims 3.
The website says that the minimum for Windows Vista is:
"2.4 GHz P4 processor or equivalent
1.5 GB RAM
128 MB Video Card with support for Pixel Shader 2.0
Microsoft Windows Vista Service Pack 1
At least 6.1 GB of hard drive space with at least 1 GB of additional space for custom content and saved games
For computers using built-in graphics chipsets under Windows, the game requires at least:
Intel Integrated Chipset, GMA 3-Series or above
2.6 GHz Pentium D CPU, or
1.8 GHz Core 2 Duo, or equivalent
0.5 GB additional RAM"
Your CPU is 1.66.
However, I also play on a Dell, with similar specs to yours - though my CPU is 1.8 and I have 3Gb of Ram - I've just looked on a recent crash file of mine. Although it has different information, I noticed that my Windows version is later than yours and It also has Service Pack 1.
If it is easy for you (or a friend or parent), perhaps you could try updating your Vista version? Also make sure you have the latest drivers for the Intel integrated graphics. Then, when you go into the game, make sure that, in the options menu, all the graphics settings are set to low or off and the boxes are unticked.
This may not work but, if I were you, I'd be tempted to try. Good luck.
Edited:
I play in full screen mode with a resolution of 800 x 600. (This is also set on the Options). I don't have any other programs open whilst I am playing.
My crash problems, when I get them, are to a black screen. I think that the laptop overheats. I had to buy a cooling pad. It doesn't crash so often now.