Take Testinz advice and just use the built-in windows tools to remove the unwanted partitions. If you're re-installing, as mentioned, windows should notice the partitions. Just be sure to pay attention while installing.
I would agree that partitioning does not have the same meaning that it used to, but it is not useless. A 80 GB harddrive should be partitioned at least into 2. Not only does this make it faster when you want to defragment just that partition/logical drive, but also gives you a secondary partition where you can keep your important documents on, and install those huge games onto.
I always point the "My Documents" folder link to the secondary partition. Whenever I re-install XP, I just re-link it to the second partition. This way you can re-do your C: drive as often as you want.
Not that it is necessary. These days with XP I don't find myself re-installing unless I get a new motherboard/cpu combo. With a laptop, that is rather unlikely.
80 GB should be 20gb/60gb.. or 20/30/30. If you do lots of downloading (newsgroups anyone?), you will be unraring and deleting stuff on one of the partitions all the time! You'll want to defrag it often so you may want to not have any games or apps installed onto it.
I am getting the 60GB version myself, and most likely will do a simple 20/40 or 20/20/20.
thanks for the tip about the lost 3.5 gig!