Any *nix system uses a different setup than Windows for denoting drives. There are no A: C: or D: drives with Linux. Instead you'll find that 'everything is a file' (and I mean everything ... every system process and all your hardware!)
Assuming you have just one hdd it will be known as hda. A secondary drive as hdb. Instead of a C:\ drive you have partitions ... Typically these are as follows:
/ = root (your system files are here)
/home (non-system files)
Many people have a separate swap partition as well and people have different preferences for setting things up.
Networking is very very possible with Mandriva, but that could be a big topic! You need a tutorial or a book rather than me and this thread.
There's more than one way to reboot. Log in as root and type init 6
My information here is very basic, but I don't want to overload you with information.
EDIT: Open a terminal and type df to see the size of each partition. To visit directories and files within partitions you'll need to learn some command line basics. Check out the tutorials section of these forums or search on Google. Welcome to our world!
