When you say "you cannot access them", what do you mean?
And why are you trying to set up pppoe? pppoe is an method of connecting to the internet, and last time we talked you were using dialup, which doesn't need pppoe.
IF all you want to do is to share files between machines, then you need to enable file sharing on both of them. On your windows machine, you'll need to share a directory out (right click on it in explorer, select "sharing", follow the prompts), and on linux you'll need to install samba.
... and configure sharing. In Ubuntu 8.10, it seems this is also as easy as find the directory you want to share in Nautilus, right clicking on it, and selecting "Sharing Options", and following the prompts. You said you were using Hardy, it may not be the same there, I can't easily check at the moment.