If your superhub is not falling over every ten minutes
then the wretched device is not responsible
for home networking problems.
Some thoughts off the top of my head:
Don't use wizards
Disable/uninstall any software firewalls you have installed.
In XP to share a folder or a drive right click/properties and initiate folder sharing. It is quite straightforword.
In Win7 to share a folder or a drive right click/properties/Security/Edit and configure/introduce -Everyone- to have Full Control in the permissions.
On both/all connected machines, from networking properties configure all adapters link speed/duplex to their auto settings.
Hopefully......when you look in network (win7) neighberhood (xp) you should be able to see other computers on your network listed by whatever names you gave them.
To share, open the relevent folders and drag files across.
When you get that working on ethernet you can start thinking about wireless.