The Easy Debian image is not self-growing. It has a fixed size of 2GB, which is the maximum of what you can get when running it from your vfat-formatted MyDocs partition.

The best way to free some space is to run apt-get clean once in a while, which will delete all the files in /var/cache/apt/archives.

If you need more than the 2GB of the image you either have to move all it's contents to a bigger image or get rid of the image altogether by copying it to a folder on your N900.
Either way you'll need another file system than vfat (or ntfs) for that. I'd suggest to use an ext2/3/4 -formatted µSD card.

btw: For Squeeze only Debians x86 variants get long-term support [1] and I haven't heard that it would be any different for Wheezy. So while armel/hf might still profit from this as usually the packages for all architectures are updated, it technically has no LTS support.


@wicket:
I haven't investigated yet but in DebiaN900 my wifi dies after some days (probably a week) of uptime. and I can't bring it back without a reboot. I believe it's not related to the transfer volume as most of the time the device is just idling on my desk.
Just mentioning as it might be relevant for server-tasks.


[1] https://wiki.debian.org/LTS/Using