If you have installed Mandriva to your eee using the 'Free' or 'Powerpack' editions, then the installer will have automatically installed the kernel-laptop kernel which is a kernel optimised for laptops with support for 4GB of RAM. (Note: In Mandriva 2009.0 the kernel-laptop is no longer differentiated from the kernel used by desktops).
If you have installed from the 'One' edition, then it will have installed the kernel 'kernel-desktopi586' designed to operate on the widest possible range of hardware, namely Pentium I CPUs and will support only 880MB of RAM. eeePC users with more than 1GB of RAM who have installed from the 'One' edition will therefore need to switch to the kernel-laptop kernel to use their full complement of RAM.
All eeePC users who have installed Mandriva 2008.1 are advised to upgrade their kernel to the latest version on the Mandriva update mirrors because the revised kernel contains a number of bug fixes and improvements, especially for eee 900 and 901 which were not released when 2008.1 came out.
The updated kernels are on the Mandriva online repositories. To enable them open Mandriva Control Centre>Software>SoftwareManagement>ConfigureMediaSources. Select 'Add>FullSetofSources' you will be prompted to select a repository mirror.
You should do your updates regularly. The act of performing updates will cause your computer to fetch the latest list of available updates from the mirror. Mandriva Control Centre>Software>SoftwareManagement>UpdateYourSystem
Mandriva uses 'meta' packages to define a group of packages. So for example the meta package 'task-xfce' will cause all the packages required to run the XFce Window Manager to be installed. The meta package 'kernel-laptop-latest' is a package which will cause the latest kernel defined on the update mirrors to be installed. Install or upgrade this package using the GUI Mandriva Control Centre>Software>SoftwareManagement>InstallandRemoveSoftware. You should also install or upgrade the package madwifi-kernel-latop-latest. This meta package will install the madwifi kernel module for the new kernel. If you do not install this package you will lose wifi.
On rebooting you will notice new menu items in Grub. There will be an item to point to the old kernel so you can still boot it if you wish, and one to point to the new kernel. The default entry 'linux' will point to the new kernel.