As far as Windows 'seeing' the Linux partition as D:, there is an option in LiLo (type
man lilo.conf) to hide certain partitions depending on which OS you choose to boot. It sounds as if you
may have a problem with the partition-map (the bit that shows which partitions is of what type).
As far as connecting your Linux box to the rest of the network, you want to read up on
SAMBA. As you can see, there's plenty here to be getting on with.