Sorry to double post, but I've been reading around in google about clearing RAM and that kind of stuff and I have a quick update:
I found about a little program called MemoryCleaner. Several reviews and articles I found said it was useful and safe, so I gave it a try. I had just restarted the laptop, and still, when I opened MemoryCleaner, the memory usage was around 65%, so I don't even want to know what memory usage I have while running The Sims. Anyways, this awsome little tool has an option to keep clearing RAM every 5 minutes, or everytime the memory usage reaches 80%. I managed to lower my memory usage to aroung 58% just with 2 clics! That is obviously while not running Sims 3 or any other similar program, though.
Then I kept googling around and found about msconfig and how to eliminate unnecessary background programs. I also found a website with an awsome list about most common background programs and whether they are necessary or not. So I unchecked everything I could (Photoshop, Itunes, Skype and a whole other bunch of trash), leaving just the necessary stuff and some stuff I wasn't sure about. I restarted the laptop, checked my memory usage again and it was 45%! Amazing!
Anyways, I had to leave some programs running on the background because I was afraid to mess things up. Most of them are related either to CyberLink or to Realtek. Could someone tell me if they are necessary as background programs or if it is safe to uncheck them from the list? My guess is that these programs are the most-RAM-consuming of all, but for what I read they are related to graphics and sound stuff so I didn't touch them. I was kind of afraid they were needed for The Sims to run or something.
I have yet to try of the game still crashes or not, but still, it is good to know my poor laptop is suffering a little less.
Thanks again to everbody