Please help cannot connect to a Win XP share folder

I have Snow Leopard on my iMac, and a Win XP Home SP3. I have shared a folder on my Win XP, I try to connect to it via finder on my iMac but says "server cannot connect".

I can ping my PC from my Mac but not otherway, I turned off firewall on iMac and can now ping - 1st problem why? And how to fix it/allow iMac firewall to accept a IP address

I cannot ping from my DLink DIR635 router to iMac if iMacs firewall is on. Why?

When I connect to server on iMac I use the IP address of Win PC, it lists the share names, I try to connect using my iMac u/n and password, also tried windows u/n and password but get same error, server cannot connect..

My Win PC Firewall is set to accept iMac IP and it does.

I searched and searched google, tried everything I know. Can someone please help
Cheers

 

Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_1 like Mac OS X; en-us) AppleWebKit/532.9 (KHTML, like Gecko) Version/4.0.5 Mobile/8B117 Safari/6531.22.7)

Well spent all w/end on/off and cannot get it working, any hints/help/tips gratefully accepted.

Cheers