I currently have a PS3 and I had a touch, I'm going to be getting the iPod Touch again soon and plan to get the xBox 360 sometime after that. I also have a netbook, so I will throw in my 2 cents here.
Obviously they are two totally different things, so it is really hard to determine which is better and such, so in the end it all boils down to what you really want.
First, you mentioned you may get the PS3 because of price drops, but there are also rumors that the xBox may have price drops as well, so I'm not sure if you know that or if that would help you make the decision, but that is what I've heard. I have the PS3 and I really like the system, but for me personally, it doesn't have as many games as I like on it. I usually play Wii over the PS3, but I still like having it around for another option and I also use it as a Blu-Ray player. I think for the xBox 360 is going to be a similar situation to the PS3, but again, I like to have the option, so it is still something I would consider. If you are a gamer and you want to update your system, then the xBox and PS3 are a great way to go. When I got my PS3 I only had a tube tv in the room I planned to use it, so for a while I had it on my main plasma tv and then once I found a tv I liked I put my PS3 in the room I wanted. I think the great thing about the new systems is that they have such great graphics, so I think you may miss out on alot of the features of the system without a good HDTV. That's not to say that the games aren't great anyway, its just having a nice TV makes it that much better.
When I had the iPod Touch (for about a month after release) I never really put it down. I found myself constantly finding things to do. There are so many apps available that it makes the device that more interesting and unique. One thing to consider, while they aren't as good as what you get on an actual gaming console, there are alot of really great games in the app store and they can be quite fun and addicting. So, if you can't get both devices, at the very least the iPod would be able to give you a little bit of everything that you would need. The only reason I got rid of my iPod was because I was having problems with it and the store I bought it from couldn't get anymore in and none of my local stores had any and I didn't feel like ordering it. As I mentioned, I'm going to be getting a touch here soon, the only reason I don't have it was because I've been deliberating getting a smartphone instead, but when it is all said and done the iPod Touch wins in my opinion, so I'm going back.
As far as a netbook, I have the Acer Aspire 1, I really like it. It is a great little device and is as easy to take around as a hardbound book, so never really a problem in my mind. While it isn't going to win any speed tests, the netbook does run pretty fast, so for the most part it isn't a pain to use it. I like to take it with me to surf the net if I go to a restaurant with wifi, or do a little work on. It is also nice for when you are watching TV but also want to be surfing the net or something. I have two other laptops that are really more of a desktop replacement, so the netbook was a good choice for me instead of using one of those laptops on the go. You mentioned you would want to use this in place of the iPod Touch for school and such (at least this is how I understood it) if your main purpose would be to keep your homework assignments and things organized, I don't know if this would be my first choice. First, I don't really know of any good scheduling programs, but I'm sure there are some out there. Also, it is a really small laptop, but it isn't as portable as the iPod Touch so you will need more space to take it around with you and it also isn't as convenient to pull it out and put in assignment in and things like that, especially if you don't already have the laptop ready, it does take a little time for it to be functional after waking up. If you, however, are looking for something that you can use to take notes with, as well as stay organized, then this may be a good choice. I find the keyboard really easy to use and it would be perfect for having something to take notes with. Just be sure you get one with a good battery life if you will be using it for the course of your day, the Acer in my opinion doesn't get the best battery life. The netbooks are great devices but not meant to be powerhorses, so they are not lightning fast, can't run everything a normal computer can and some things they just can't run as well, if you plan to game you can, but really basic games are about as far as you can go.
So really, I think all 3 devices would be a great choice. But, you have been saving up the money, so it just is a matter of what you really want and what you really need. I don't think you will be disapointed with any of the options, I have used all three and they are all great.
Good luck with your decision!
