"Windows 7 laptop" doesn't tell us much.
I'm not sure if it's the same for Win 7 and Vista, but I suspect it's mostly the same. To find (most of) your computer specs, go to "control panel", and click on the "system and maintenance" and move on to "system - view amount of RAM and processor speed".
Memory (RAM) and hardrive isn't the same, but people seem to confuse them a lot. Harddrive is how much space you have to store files. Comes in anything between 200 GB and up to several Terrabytes. Memory/RAM is... harder to explain, so I'll let eHow do that for me,
here. Usually comes in 512 mb to around 4-8 GB, depending on how new it is and what the computer is built to do. A gamer PC (usually over 4 GB, often dedicated graphic memory in addition) needs more memory than a regular school PC (rarely more than 2-4 GB).
A regular laptop for school use is usually not built to deal with games like Sims 2 or sims 3. My own laptop can barely even run Sims 2 CC-free any longer. I run it very hard while it still worked (everything up to FT, loads of CC), so I'm not surprised it's refusing to run it properly any longer.
I've got 4 GB memory on my PC, built for games and 3D design (and I wish I had more, because it's barely enough sometimes). I know Vista needs about 1 GB memory to run properly, which leaves me with 3 GB to do other things. Sims 2 gets a hiccup, and crashes if it used more than 2 GB. With a fix I did, it now does it when over 3 GB. That leaves very little, if anything at all, to other tasks.