Totally depends on what you are using it for.

Netbooks usually have slower processors and less upgrade options.

Laptops usually have a bit more power, and usually have additional options.

The trade offs are of course price and battery life.

If you are just watching a movie or connecting online or checking e-mails, a notebook may be all you need.

If however you are doing heavy processing, giant worksheets or databases, graphic intensive stuff, etc, you may want a small laptop with much more power then the netbooks. Most netbooks currently come with XP or Linux on them, if you need Vista it may be too little power for it. Many of them have smaller solid state drives, 8 GB, 12 GB, etc, though some have real hard drives in them.

For probably 90% of what I need a small computer for a netbook will certainly take care of it, but if you have different needs, maybe not.