Hi.
Maybe no solution, but I got the same error and if I tried again, it works.
At the moment it works with eclipse 3.4 for linux under KUbuntu 8.10.
(Ready with installing at the moment

)
But under windows xp sp3 i got it running also. (Windows is my favourite, but I also wanted to try it on Linux

)
I tried the same url i wrote in my last post. Just play around and try again.
Maybe anyone other has a solution for this problem.
Greetz
BlackDragon
[EDIT]
Try to download ADT manually. Visit
http://code.google.com/android/intro/installing.html or get it
here.
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Troubleshooting ADT Installation
If you are having trouble downloading the ADT plugin after following the steps above, here are some suggestions:
* In Step 4, try changing the remote update site URL to use http, rather than https.
* If you are behind a firewall (such as a corporate firewall), make sure that you have properly configured your proxy settings in Eclipse. In Eclipse 3.3/3.4, you can configure proxy information from the main Eclipse menu in Window (on Mac, Eclipse) > Preferences > General > Network Connections.
If you are still unable to use Eclipse to download the ADT plugin, follow these steps to download and install the plugin from your computer:
1. Download the ADT zip file (do not unpack it).
2. Follow steps 1 and 2 in the default install instructions (above).
3. In Eclipse 3.3, click New Archive Site....
In Eclipse 3.4, click Add Site..., then Archive...
4. Browse and select the downloaded the zip file.
5. Follow the remaining procedures, above, starting from steps 5.
Note that to update your plugin, you will have to follow these steps again instead of the default update instructions.
Note that the "Android Editors" feature of ADT requires several optional Eclipse components (for example, WST). If you encounter an error when installing ADT, your Eclipse installion might not include those components. For information about how to quickly add the necessary components to your Eclipse installation, see the troubleshooting topic ADT Installation Error: "requires plug-in org.eclipse.wst.sse.ui"
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[/EDIT]