MBP won't see PC on network

I am running Macbook pro which accesses router wirelessly. My PC is connected to router via ethernet.

I have just upgraded MBP to OSX 10.5. (havent done 10.5.2 yet). Previously in 10.4.X the in the finder window the PC shared directory always appeared when connected. Now i cannot see it at all in the finder and do not know how to make it appear.

I have tried the following:

- Creating new network through network wizard on PC Desktop and enabled sharing for relevant folders.
- enabled sharing on all relevant folders on desktop
- enabled file sharing, printer sharing, internet sharing and bluetooth sharing in System Prefs on MBP.
- tried to enter IP address of desktop in System Prefs>network>Advanced>wins

I really am stumped and frustrated as it is severely inhibiting my workflow.

Any suggestions?

In the System Prefs>network>Advanced>wins did you see your workgroup in the drop down menu It maybe just that that is your problem if you can't see your PC. Quite a few have discovered this as the fault.
I have a software firewall on my laptop which I forget to turn off sometimes too

http://www.mac-forums.com/forums/showpost.php?p=633728&postcount=8

well i don't see the name i set for the workgroup. And i can't delete the netbios name, which i assume is the Macbook's.
Furthermore there is no firewall in place.
Stumped!