Yeah, you've got to unzip the rootfs archive on to your new ext3 partition.

You have to have the rootfs archive downloaded to a spot you can access from Linux. You also have to have the new ext3 partition mounted.

If I were doing this again, I would boot to the linux livecd, like Mint, and open a terminal.

I always had mine mounted to /mnt. I don't remember what the livecd uses, you'll have to check. So this is what I would type if I were doing this:

cd/folderwhereIdownloadedtherootfs

sudo tar xjvvpf ../home/USERNAME/DesktopNITDroid-N900-0.0.3-1-Demo.tbz2

That last command is copied directly from the OP. It works from the livecd xterm, but not from the N900 xterm.

Sorry I have to go to bed. Someone else will be along in the morning.

Good luck, man. BTW, are you the guy who started the pininthemap thing? That's a cool map. There's nobody within like 500 miles of me, though.