Update: I used to be able to ping the Amiga from the laptop but not the laptop from the Amiga. No changes have been made except cleaning up the IP addresses (there are no conflictions) and i cant ping either machine at all.
There is a option in the extended XP TCP/IP settings to allow pinging. The important thing is that the ping is working. After that you have to check if the hostnames are working right with ping Amiga4k or ping PC.
I did it some days ago! And setup my A4k working with Samba on the PC-Network. :-D But it was also frustrating...
Now I can connect to the Amiga using only one account inside XP. I disabled the guestaccount.
Here is a picture from my smb.conf
