Windows 7 - Sharing a partition between Windows 7 and Vista. Sigh..

I am really getting angry (nicely said) about getting my partition shared and working...

Current setup:

Home PC: Windows 7 Ultimate x64
Work PC: Windows Vista x64 Professional
Router: D-Link DIR-655

What am I trying to achieve; I want to share several partitions on both my Home PC as on my Work PC, so they both partitions can be accessed by both machines for copying several files and stuff which I need to be copied.


Problem:

I am getting the following error whenever I try to connect to my Work PC (Vista) from my Home PC (Windows 7): 0x80070035

When I try to access a partition from the Work PC (Vista) on the Home PC (Windows 7) I can browse through the folders, but cannot copy anything to it; it complains about having insufficient right or some other crap.


Things I have tried:

Googling the living **** out of me, but no luck. I found a few websites, but nothing provided me with a working solution... I already disabled Windows Firewall on both PC's. I am really getting pi**** about this, normally I am not that short-tempered, but this is really getting on my nerves...

I don't know how to get this working properly... And the weirdest thing is, I never had any of these problems when I still had Vista installed on both PC's. I only recently purchased Windows 7 Ultimate and installed it on my Home PC, cause it's more up-to-date and provides better "graphics"- and "gameplay"-experience in games...

The router is working fine, cause nothing has been changed when I was still working with Vista-Vista, but the problems started when I started using Windows 7-Vista.

Anyone can shed some light into this, or provide me with a solution how I can get the shares back working, so I finnaly can finish setting up my Home PC?!

Thanks in advance.