Can I ask, did Starhub have any prepaid internet?
If I want to Compatible with laptop, so should I buy the broadband?
Depends on your requirement.
If you are always "on-the-go" with your laptop and constantly needing internet access, mobile broadband would be more suitable.
If you are only using the laptop at home, you can either subscribe to the mobile broadband or to the broadband (MaxOnline) service.