The difference of the method is not that one is outdated and the other one is state of the art. Well, simply there is no such thing in a years old 'smart'phone.

This is the microSD card setup on the default internal card:
The first partition is a data partition, aka MyDocs, the second partition, aka optfs, is an extension of the system setup for applications to install to. The third partition is the very essential swap partition. Because of the RAM shortage, the N900 does all weird stuff, if this partition is missing.

The approach of the nokia.europe forum is to ignore the low space for installable applications because of the small microSD card used. It only provides some small data space and the swap partition. No extra space for installable applications!

Here in post #10 of this thread the whole system is cloned to an external card giving you all the partitions, that the N900 comes with, MyDocs, optfs and swap!

I would suggest, since Maemo is a linux based system, you give some time and effort to learn your first steps in any Debian- or Ubuntu-Live-CD or -Live-USB-stick. This will provide you with the tools to manage the different tasks to tune the N900. The learning curve for beginners might look very steep indeed, but it is only steep! There are no custom ROMs for every situation to use because, you could do most of the things right from the Terminal, this way the 'culture' for the N900 is more a DIY-type of culture.
In Linux you have simple command line tools for cloning one card to another and resize the layout according to the larger space.
Also the procedure to flash the firmware seems to be much more reliable in linux!

Here is the Wiki article about resizing the partitions with the linux application Gparted: http://wiki.maemo.org/Repartitioning...ng_made_simple