Problems after PC crashed and recovered!

Hello,
My mothers laptop..with windows xp crashed. We tried a system restore, didn't work. We recovered it with the option it has to do so without using a windows disk. The problem now is, it appears to have VERY LOW MEMORY. We don't have even Half the things that used to be installed in it, where it still had memory to spare. Such as the kids video games like...Civilization 3...and 4...and such. So, im not very computer savvy...and We constantly get the LOW DISK MEMORY bubble at the bottom right corner. If we try to install something, it tells us "Not enough memory".. Why does it suddenly have no memory? How can we fix this? Thanks!
Andres