This is a great question my friend, and one that I can provide an answer to. I have been keeping an eye on the netbook market for some time, and keep crossing my fingers hoping for a Apple netbook.
The first think I want to say is that not all netbooks are windows machines, in fact you can get most of them loaded with a linux distro such as Ubuntu instead, also the Google OS Android is starting to be shown on netbooks as well (If you look at the Computex footage). I have a duel boot system with Windows and Xandros Presto (An instant on Linux distro that saves a lot of battery power). I am soon going to install Ubuntu on it for now they have a special re-vamp for netbooks.
Now, let us get back to the hardware of the netbooks. You can choose from just about every major computer manufacturer out there. Everyone is joining in the market. It all comes down to what you want in the computer, what type of beating it will go through. I can say netbooks are well worth the price for a student's computer to take to class to jot down notes, and they run power points off of them pretty darn well.
So far I have personally bought three Acer Aspire Ones. Two of the first generation 8.9 with a two cell battery, and the latest being a 10.1 with a 6 cell battery.
The first thing I would say is to keep an eye out for the battery, on a two you are most likely going to get two hours of battery life on power save mode and a dimmed backlight, a general rule of thumb for netbooks, the cells usually are the same number of hours you will get off of it. My six cell at best will get about six hours of use.
Most netbooks have the same internals as well. Intel Atom 1.6GHz CPU*, 1GB RAM, 120GB HDD, 2 Cell Battery, Mobile Intel® 945GSE Express Chipset, or a Mobile Intel® 82801GBM Chipset. Newer models are starting to see the Nvidia ION chipset being put into use, it is very powerful for a netbook chipset.
All the companies have something good to offer, so I'll list them below and what is so great about them.
Asus Eee: The Eee PC is one of the first (well if you include the newton as a netbook!) while some of the early models feel a bit cheap (plastic bends and creeks on opening), they are very small and light. On top of this they are some of the cheapest on the market. A lot of new models are always coming out for this one so do your research on this one to find the best buy!
Acer Aspire One: The Aspire One series has gone through a few general re-vamps but nothing to serious. The first models are the 8.9". They soon became widely popular over the Asus and toped the market as the best selling netbook. However, the first models had a problem with the hard drive being mounted to close to the speakers, at max volume you could throw your disk off center and it was the end for that hard drive. They soon came out with the newest of the bunch in the form of the 10.1" with a six cell. I just got one a month ago for the price of $350 which is a pretty good deal for the battery alone. Soon it is rumored that in the fall a new model will come out with a faster CPU, Android the Google OS, and maybe the ION chipset by Nvidia but we can never be to sure.
Dell Mini Series: Dell has several different types of netbooks under its Mini series, all are about the same basic layout for netbooks. One thing they are doing though is making netbooks for the student market. Dell offers netbooks that are a bet bigger is size but are made to take a good beating, and they come in some sweet colors.
Samsung NC10: This sole model is the only one offered by Samsung. It comes with the standard layout from above, nothing special inside. However, this thing got some pretty good reviews. It costs a little bit more then the bulk of them, and I would take a look at it.
HP Mini: Another "Mini" I know, the HP Minis are small, really small... they are darn thin. From looking at it for the first time I was a little shocked. They have the standard layout as most. The disadvantage with this one is the cost for a new battery can empty your wallet pretty fast. The Minis also look pretty slick which most netbooks lack. Take a look at this one.
MSI Wind: I have heard a lot about this one but nothing really great. I don't know what to say about this one really... I wish I did.
Levino Ideapad S10 Netbook: Sure this guy might be more expensive then all the others on the list but it really is worth looking into. This is the first netbook on the market to have the ION chipset on the computer. Making it the first and only netbook capable of running full 1080p video and games like Half-Life 2 well over the 30fps marking. Take a good look at this one, it is an Ideapad, you know it is quite durable on top of everything.
My final word is to go out and actually handle the computers as well. Feel the weights, the thickness of all of them. Also compare the specs for new models are always coming out and in order to not be scammed out of your money you need to make sure that you know all the information.
*Intel Atom CPUs are soon to be discontinued to make way for the new core i3, and core i5 CPUs.
Footnote: I did not include some models simply because they went over 1k for a netbook, a price like that defeats the whole goal of the netbook market.
