I was trying to set up a network of 2 computers via the hub in the router. It wasn't easy at all.
It was supposed to be pretty easy as Windows has wizard to help me with that such as setting up computer name, description and workgroup etc. It went error free but I still couldn't find the other computer on the network even with them hardwired.
I turned to the Free version of Network Magic at last as I have it installed on my notebook already further to recommendation by D-Link.
I have both computers connected before I felt too tired and transferred some files. I did it also on wireless mode from my notebook.
It turned out that, while I was on my bed still thinking about this hassle, it was Windows firewall that caused all these problems. I used Live OneCare on my both machines and I had to turn off the firewall completely on the receiving PC before transfer can be done. This could be the reason why both PC couldn't see networked computers under the same workgroup even though the setup was error free.