batch file to install sp6a to NT4clients

I am looking for a file to install service pack 6a to my NT 4.0 workstations though a script withouht user interface. I also need this file to somehow check the existing service pack to make sure it won’t be run more than once. I also have other files that are updates I would like to have atomatically installed thought a batch script file but I only want them updated once! The only thing I came up with so far is the following, and I don’t even know if this will run right!

net use U: \\primary_server\Updates
U:
cd\NT40
dsclient /Q /T:c:\Temp /C
cd\nt4sp6
nt4sp6
update -u -f -n -o
net use /delete U:

Thanks sooo much for everyone’s help! Even if you can give me a little insight it is greatly apreciated!