I like the intel drives for laptops. They sip power. They have great iops. Their downfall is in writes which is, imo, less critical for a laptop.
However, price per GB you can get better performance from a sandforce 1200 based drive. Such as the OCZ V2 or Agility 2, C300 (as anort3 said), etc.
Size depends totally on you. An x25-v40 may be just fine. It will boot almost as fast as the m80. Your OS, office, minor programs, will fit just fine. Your files can sit on the 500 ext. drive.