Network Problems!

I need some advice about my home Network.

I have a Linksys router with 4 items connected. PC(vista ultimate), laptop (vista home Premium), Buffalo network drive (early model) and a linksys media center. linked all by network cables.

My Pc can see and deal with the Buffalo and Media Center but can not map to the laptop.

the laptop can map the PC but can not see the buffalo or media center

The Media center can see the PC and the buffalo but not the laptop.

I would like to be able to get the PC to see the drives on the laptop...

thank you