I'm no expert but I doubt if NXT-G program running on a NXT can send a file directly to a computer. The only references I can recall are using NXT-G to inspect the contents of the NXT and uploading/ downloading files that way.
There is a guide to datalogging with NXT-G here http://www.teamhassenplug.org/NXT/DataL ... ogging.htm
and that suggests using NXT-G, as opposed to the program running on the NXT, to transfer files.
I think you would have to use one of the other programs (NXC, LabView or RobotC, etc.) to do what you want.