I don't know Printmaster from a head of cabbage.
I am saying that if that "projects" folder is somewhere within the installed program (eg, probably somewhere under C:\program files), then I suspect you may have issues if you try to copy it somewhere else.
I am assuming that the "projects" folder of the Printmaster program appears under C:\Program files somewhere on the XP computer.
If these saved files were saved elsewhere, outside of C:\Program files, then presumably they are "data", just like an mp3, a picture, or a letter to grandma. In that case, I would guess you could then access them with any new installation of Printmaster.
That is the way installed programs are typically handled, but as I say, I know absolutely nothing about Printmaster.
For instance. If you have Photoshop installed on computer A, you can't simply copy the Photoshop folder under C:\Program files on computer A to another machine or installation and expect it to work.
You might (??) be able to copy the individual files within the projects folder to the same folder within the Windows 7 install and have it work--as opposed to the entire projects folder--but that is just a wild guess.
But I may be misunderstanding you completely.