How can we map a network drive if we have not established a network among computers ruing in Windows XP and 7?

I am writing to seek advice whether we can map a network drive without previously establishing a network among computers ruing Windows XP and 7. The network here refers to the local area network (LAN) or wireless local area network (WLAN) linked through a router.

For these LAN and WLAN to be established, besides the use of workgroup among Windows XP, whereas Homegroup among Windows 7, what can be used to establish a 'network' to 1) allow files, folders, and printers to be shared between Windows XP and Windows 7?; 2) allow mapping of network drive to be performed?

Thank you.