Getting GUI (step 1)
The biggest obstacle here is that the Xorg packages are listed as "experimental" and are not readily available with the standard configuration of apt-get. So, follow the instructions here to gain access to these experimental packages. Skip the bit between "To activate a package..." and "...as usual". It's much easier to just use the -t option to apt-get when you want to install one of the experimental packages.
Download the xserver-xorg package by running
apt-get -t sarge-backports xserver-xorg. You can accept all the defaults for the X configuration process and just choose the "Vesa" driver for the graphics card.
Download the corresponding source code - we'll need this when we come to building the video driver. I don't think there's a Debian package for this code, so we'll have to download it the old fashioned way. Currently the xserver-xorg package is 6.9.0 and the corresponding source is available here. You can check the version of your xserver-xorg package in aptitude. Expand this file into /usr/local/src.
If you check the disk space with
df --si /, you'll see that we're up at around 1.2Gb. At first blush, this is pretty bad. But do a
/usr/local/src, and you'll see that over 750Mb of that is just source code, which will be removed long before we cut over to compact flash. So we're actually doing OK.
Now that we've got the X server up we just need a Window Manager. That'll be the next post.