Accessing PCs over the Workgroup

Hi,
I have a workgroup of 10 PCs. If i share a folder on one of the PCs and access the same from a different PC, I am asked to enter a username and password.
After doing so I am able to access. On rebooting the PC, I am asked to enter the username again to access the folder of another PC.
This problem also reflects in shared printer for which each time i have to enter the same details.

I am not able to access the shared folders directly without entering the user details.

If somebody could help me on this topic, it would be great.
Thanks
Vivek