iMac and Windows 7 Network

I've just purchased a new 27" iMac and am trying to connect to a Windows 7 on my home network.

I'm running a wireless home network with Internet access for 3 iPads, 1 Windows 7 PC, an old Vista PC and other wireless devices such as Wii, Xbox, Samsung Tv and an Apple TV. All work fine on their own, and the router shows all working ok over the network.

My issue is that I've not been able to connect my iMac to the Windows 7 Ultimate PC. Both are under the same Workgroup name. I've been able to connect from the Windows 7 to the iMac, but cannot do so via from the iMac to the Windows 7.

The directories / drives on the Win7 are all shared. From the Mac I'm entering the command smb://office-PC/photos. Where office-PC is the computer name and photos is one of the share drive names. I get a user prompt message, where I enter the PC username and password, but then I get a message about no permissions.

The username and password is correct as its the same ones I use when login onto to the PC directly.

I've been using PC for quite sometime now but this has me stumped. It has to be something very simple I'm missing, but has me beat.

Appreciate any ideas.

Darran