I had a similar issue and did some research on netbooks. Here is what I can recommend you try first:
1. Battery life. get something with a 6-cell battery or larger. There is no sense in getting a netbook if you're going to have compromised battery time. a 6cell will get you between 6 and 11 hours of battery time depending on the computer and your use and settings.
2. screen size and resolution. Most of the latest netbooks come with 600x800 10.1" screens these days. The days of smaller screens have largely been phased out. a 10.1" screen is pretty good, but not with 600x800 resolution. that resolution tends to be good only for larger icons and font sizes. the problem is that if you use full size rendering on a 10.1" screen, screen real estate becomes a problem (stuff gets crowded or falls off the edge of the screen). If you scale things down in order to get better space, everything becomes fuzzy and somewhat piexelated. I highly recommend that you look for something with a higher resolution screen, such as Dell's mini 1012 which offers a 1366x768 HD screen option. The higher resolution will allow you to scalle the screen more to your liking without pixelation. The internet will also render much better.
3. USB ports. Most current netbooks are using some form of INtel's Atom processors with motherboards with 2 or 3 USB ports. Go for 3 USB ports.
4. Processor: Try going for the highest spec machine processor wise. most netbook processors are single core and currently clock at 1.6 GHZ. I keep hearing buzz about faster or dual core processors, but have yet to see a product hit the market. I believe Intell's latest N455 processor supports DDR3 ram.
5. GPU: This is a bit of a mixed bag, and you'll really have to do your homework on the different graphics card that come with netbooks. As a general rule, you won't get a lot of processing power in netbook graphics cards, but some are definitely better than others. If you're into tinkering, keep in mind that some offerings solder their GPU's to the board, while others have connectors. It's up to you to decide which will work best for you. some companies, but not all do have optional cards with higher specs. Fro example, Dell bundles such a card together with the higher resolution screen in their 1012.
6. RAM: Because of microsofts licensing requirements for Windows 7 starter, most manufacturers are not allowed to sell netbooks with more than 1GB of ram installed, even though most of them support 2GB. Count on having to upgrade the RAM (single 2GB chip). Find a netbook whose RAM access you are comfortable with (some have readily accessible Doors, while others require pulling the keyboard to gain access).
7. Hard Drive: Some will try and sell you on a solid state drive. I find that they are expensive, and don't have nearly as much memory as I like. They also generate heat, and since most netbooks do not support internal fans to dissipate heat, this can make them annoyingly warm (consider investing in a chill pad if this is a problem for you). You can find some very large SATA hard drives in the after market, but most netbook makers tend to top their offerings somewhere between 300 and 500 GB, which should be more than adequate for most folks.
8. Bluetooth. Not necessary, but I enjoy having it to run a wireless bluetooth mouse, thus keeping my usb ports free.
9. Touch pad: they come in a very wide variety. I would advice you against getting one in which the buttons are just an extension of the same surface of the touchpad (as opposed to a raised surface or separate pieces). Got to computer stores and play with different netbooks and try different touchpads. You're bound to find one that you like.
10. Wireless card. There has been a recent shift in netbooks from using Wirless G cards to Wireless N. many makers have switched without advertising the switch. wireless N is much faster and can handle much larger files. I highly advice you to make sure you get Wireless N.
11. Price. You can do very well by shopping in the refurbished section of most large manufacturers. Just make sure that the specs match the advice above. You can easily come in below $300 if you do. If you prefer new, the advice above should put you in somewhere in the high $300's to $450. You really don't want to spend more than $450 on a netbook. for that money, you are better off buying a proper laptop.
12. Operating system. Most folks will not consider moving away from microsoft. personally I find Windows 7 to be a solid OS, but I find it to be too big and bloated for netbboks. It simply demands too much of the hardware. The cut down version (windows 7 starter), I find to be OK, but is too limited and still slow. on top of that you still have security and virus concerns. Personally I would either wipe out windows and run your preferred linux distro or do a dual boot set up with your preferred linux distro as an option. By running linux you will generally get a noticeably faster system, a safer system, and most importantly, a full featured OS (as opposed to a cut down one). For your needs, several free office systems, such as Open office and others are freely available, as are several instant messaging programs that will run AIM. Also Eclipse is available for Linux, so you won't loose any functionality in that regard. Here is a post regarding Distros for beginners that you might find helpful:
http://androidforums.com/computers/177768-linux.html#post1595995
Lastly, I would look long and hard at the biggest makers of netbooks, and shy away from the smaller makers of fancier machines (such as Sony or toshiba), as they tend to have higher prices without offering much beyond style. Look at the offerings from Dell, HP, Asus, and Acer, especially Asus and Dell since they have the biggest numbers of offerings and have large communities of enthusiasts who can help you with any number of issues you might have. I generally find Asus netbooks to be easier for beginers to work with and are a little smaller, while Dells tend to be a little bigger, require more skill to work with, but are more solidly constructed.
Good luck with your search. I hope this helps a little (at least until technology advances again and makes this post useless - maybe in 6 months to a year
).