Linker,
Sorry about the delay in responding to your post, Apr.1st was a rough day here at suck-o
Now in answer to your question:
It is possible to access another computer, remote access is already included with windows, you can also use file-sharing programs, you can even make the other computer a webserver.
You say the mission is to copy something from his harddrive. You might already know what desktop OS he is running, that he might use IE6.X for his browser.
So craft a webpage for him to visit.
This is why it is important to at least learn some code, in this case HTML, and its SCRIPT, OBJECT, APPLET, and EMBED. It also does not have to be a page on a website, it can be HTML mail.
BUT- forums (a security conscious one anyway) and email services screen for most basic malicious code, so thats where your imagination comes in..
There are other ideas for stealing a file from a computer, maybe someone will get back to you here ..
DNR