Windows 7: Network lan connection win xp and 7 computer, how to?

computer #1: windows 7 hp
computer #2: windows xp pro

I managed to lan cable connect and share folders/files between 2 windows 7
computers. And the same between 2 windows xp computers.



Then I wanted to lan cable connect and share folders/files between a windows 7 hp and a windows xp pro computer.

I tried for hours, running the same settings in circle.
At a point it worked. But I don't know why it suddenly worked.
The difficult thing was, to make the network icon appear on "the other computer".

Do you have a detailed step by step manual, on how to config settings in
order to share documents/folders/files?

Have you tried this? File Sharing - Between XP and W7 (and vice versa)