Please provide just a few details:
I assume your WinXP is 32-bit. Is your Win7 a 64-bit or 32-bit Win7?
Also, what is the printer brand/model?
Also, are both the XP and Win7 machines on the same "workgroup"?
The key is to specify the printer on XP as "shared", and then the Win7 machine should see it as part of its "Add Printer" dialog and have no problem connecting. But if there's a 32-bit/64-bit issue that's a wrinkle that needs just a bit of work to resolve.