Sharing files and folders with an XP system is not too hard to do.
There are some terrific tutorials here in the Network and Sharing forum.
In a nutshell:
1. Make both machines a member of the same Workgroup. Don't confuse it with Homegroup which isn't compatible with XP.
2. Have File and Printer Sharing enabled in the XP machine.
3. Right click on the printer on the XP box and click Shring, then enable sharing of the printer.
4. On the Windows 7 machine, you'll probably want to disable IPV6. It's only used for Homegroups and can get in the way of other stuff.
5. On the Windows 7 machine use the Network and Sharing Center, then Advanced Sharing Settings (On the left edge) to see the option on there. Look at File and Printer Sharing, Network Discovery, Password Protected Sharing, Public Folder Sharing, File Sharing Connections (you'll need to set it to 40/56 bit).
Give that a try and let me know how it goes.