If you have any Firewall or Security Software installed on those machines, pls. disable them for now.
If you're using the Windows built-in Firewall, make sure that Files and Printer sharing is Excluded.
Create Identical UserNames and Passwords on both computers.
Please compare your current configuration on how to share files and printer. Share Files and Printers between Windows 7 and XP - How-To Geek
Disable Password Protected Sharing in Windows 7: Disable Password Protected Sharing — MAXIMUMpcguides – Windows 7 tips, tricks, help, and how-to guides
Verify that you are sharing the folder to Everyone, give full access for now. Were you trying to share the entire C Drive or subfolders in the C Drive? Please share the entire C drive for now, call it C
Click on Start, type the \\ComputerName\C
- The Computer Name or IP Address of the computer that you're trying to access in your home network.
Please post an update and let us know the outcome.