If you enter the username and password (you should have a password too, although I realize you're the only user), you can check "remember this" for next time.
Accessing shares and other drives (hosted by other machines on your LAN) will only bother you once for this username and password. Not thereafter.
I myself user the same username/password on both of my networked machines (defined to be on the same "workgroup"). So the username/password from the requesting machine is in fact the same username/password for the requested machine... and I have never been asked to enter anything.
It just works. I have FULL access to all drives and folders/files on both machines from either machine (and even from either WinXP or Windows 7, booted at either machine). No confusion, no request for username/password. I am the only user.