Vista&XP WLAN connection and sharing problems

First - hello everyone!
Second - I'm a _networking noob_ who needs help.
I've just bought my first notebook, HP 6715B. It comes with Vista Business. At home I have a desktop PC (XP Pro SP2) connected via ethernet to a WLAN router (Thomson ST 780i WL http://www.thomson-broadband.co.uk/products/Details.asp?ProductID=528 ). I've added my notebook and it detected my router and connected wirelessy. Now both computers are sharing my ADSL2+ internet connection. That works perfectly. However I want to share some folders in my network. Both computers are in the same workgroup. I've entered IP adresses, gateway... in the (w)lan properties.
XP shows this error:
http://www.imagesforme.com/viewer.php?id=4475blah.jpg
Some Vista screenies:
http://www.imagesforme.com/viewer.php?id=9035mrezaaaa1.jpg
http://www.imagesforme.com/viewer.php?id=2712mrezaaaa.jpg
I've pinged the laptop from the desktop PC but it shows request timed out error.
Then I pinged the desktop PC from my notebook and it worked.
Sharing options in the network and sharing center are turned on (except the password sharing).
So I'm stucked here. Can't acces shared folders of any pc via network.

Any ideas, guides how to solve this?

 

I had the same problem with my xboxx 360 and my music. Don't know if it will work in your case, but you have to designate each folder or groups of folders to share between computers. I had to spefically share my music folder so that the xbox 360 would pick it up as a readable shared folder and stream the music from the laptop to the 360. Hope this helps.

 

Sounds like a security (FW) issue. Make sure you add a rule to allow your subnet.

 

Firewalls disabled. Same thing.