A fast google shows the 3c59x module is the ( driver ) module for your nic.
Open a konsole, and become root. Try to load the module with a 'modprobe 3c59x' command ( without the quotes ).
If that module loads, then you still have to configure the nic to get it working. Mandirva has something called MCC ( Mandriva Control Centre ). There is an option in there to configure the nic. You need to know things like the IP address you want to use, the gateway address, DNS addresses and netmask. Im sure there is an option like automatic in windoze. It is called DHCP, if you have a router and it gives your system all the correct information.
Could someone help me fix it and possibly provide a philosophical explanation
I can only guess. It could be you missed the configuration during install. It could be related to the fact that Mandy 2008 is old, and does not have the driver you need; it that nic was released after 2008, that could explain it.
The current version of Mandriva probably not have a problem.
How much less than 512 MB of ram? 256 Mb is usually enough for most distros to at least run. It may make them a little slower, do to disk swapping, but they will run.