I just tried to add a Win7 machine to my existing named workgroup of 12 computers which mostly control lab instruments within a larger departmental subnet at a university. All my machines absolutely need, and presently have, read access (only) to all my other machines' root directories. I haven't been able to acomplish this with the new Win7 machine. I have shared the "C" root via advanced sharing and with read access to "everyone". However, none of the XP machines can access it though they can see it. If "password protected sharing" in Win7 is turned off, XP's get "\\__\_ is not accessible". If "password protected sharing" is turned on on the Win7, the XPs are asked for a password and no matter what they offer, they get nothing. Each existing machine is logged on (via auto-logon)as an administrator user named for the machine, like "SpectrometerUser" for the computer "spectrometer". I'm been writing code including things like device drivers and interrupt handlers for a long time, but I'm sorry that I haven't learned more about complexities of networking permissions, policies, shares, etc. Can someone please offer simple instructions as to how I can get this Win7 machine do what is essential to my work and easily accomplished with WinXP?

Check firewall and network discovery settings in control panel