Good old fashion "workgroup" setup should still work:
1. Create identical accounts with same username and password on both (or all) of the computers, you should logon using those accounts from the get-go.
2. Set up the shares on either/both of the computers. I would suggest granting share access to the "Authenticated Users" group or that specific account. Remember, effective access is calculated from both share access and local file system permissions (most folders you create under non-special folders should inherit "Users" permissions meaning you should be able to read/write by default). Just need to make sure both permissions do not combine to less than what you want.
Caveat is the drive "hidden shares" (C$ for example) will still not be available unless you elevate to an admin token (under UAC), which from normal File/Windows Explorer windows is not possible. Creating separate shares is not that much more difficult.
Of course, if you have an Active Directory, all that stuff can be centralized but the setup cost for a full AD network is overkill in your situation.
Edit: if you are using a cross-over cable for a point-to-point "LAN", name resolution may not work until both IPs have been auto-configured and they figure out who is the master browser (or something to that effect). This can take minutes. I use cross-over when I need to transfer massive amounts of files so I make sure have monitors attach to both computers and just use ipconfig to get the IPs and connect directly using \\[IP]\share.
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