A small Zodiac/GP2X comparison:
Movies:
The Zodiac is better because it has twice the resolution. Both devices play most videos without conversion and use SD cards for storage (cheap). The Zodiac also has the (small) advantage of having two slots for SD cards. However, the GP2X can be connected to your TV, you have to decide for yourself if you think that feature is usefull to you.
Emulation:
The Zodiac has a nice selection of emulators but I have no doubt that the GP2X will be better at it pretty soon. The GP2X has the advantage of a digital stick, the Zodiac's (slightly buggy) analog stick isn't perfect for 2D games.
PDA/Organizer functions:
You can easily and quickly type texts on the Zodiac's touchscreen using a thumbboard. There is a huge selection of software availiable from Office suites to shopping list keepers and lots more. The GP2X probably won't have much in this category.
Ebooks:
Again the Zodiac has the (in this case not too big) advantage of a higher resolution screen. It can display ebooks in many different formats but the GP2X might catch up.
Homebrew:
There is quite some Zodiac homebrew stuff but the GP2X will probably get more. However, you have to take the huge amount of Palm homebrew into account so in the end both devices should be about equal.
Commercial Independent Games:
The Zodiac has a number of must have games and then there are a lot more games worth playing. I would like to see similar things on the GP2X but it is very difficult to foresee how much there actually will be. It will be difficult for the GP2X to gain as many developers because most Zodiac games run on more Palm OS devices so developers have quite a large audience. The GP2X will probably sell as many units as the Zodiac (100.000) but it will never sell more than all devices with Palm OS do together.
Music:
Both devices use SD. I know the Zodiac's sound quality is great and I guess the GP2X' will be on a similar level. Both use SD cards and support different formats as well as a power saving mode so there isn't really any difference.
Important hardware differences:
Screen: Zod has 480*320, GP2X 320*240
Controlls: Zod has analog stick, GP2X has a digital stick
Battery: Zod has internal battery lasting from 3 hours (heavy use) to ~6 hours (music playback). GP2X has 2 AA batteries lasting from 5 hours (heavy use) to 10 hours (music playback)
Processing power: Zod has one 192 Mhz ARM and a 2D chip. GP2X has 2 200 Mhz ARMs with some 2D hardware, too.
Input: Zod has a touchscreen, GP2X not.
Communication: The Zod has built in Bluetooth for multiplayer and Wifi can be added with an SDIO expansion card (expensive). The GP2X doesn't have any standard multiplayer but it might be possible to connect devices via the ext port or USB or connect bluetooth/wifi hardware. However, it will be difficult to establish a standard solution.
Both devices connect to a PC for data transfer via USB. The Zodiac uses a proprietary cable and software while the GP2X is simply recognized as a standard mass storage device.
It really depends on what you want. Well, it always does...
