For office laptop/PC, a 120/128 will be sufficient, because not many apps that required a lot of disk spaces.....
For home user, it is recommended to have a 240/256 because normally SSD is faster compare to same model with 120/128.
For now, I have these SSDs
Office laptop (win7+office): Vertex3 60GB (left 16GB)
Office laptop2(win7+office+apps): intel 530 180GB (left 101GB)
home laptop (win7+office+itunes): M5P 128GB (left 40GB)