The best way to prevent a program from
running at Startup, is to check the program's own options for a way to
prevent this. Most good quality programs will provide an option for
this.
If you can't find the option there, click
Start, Run and enter MSCONFIG. Go to the Startup tab, and uncheck the
item there. This method is not always 100% successful. An example is a
program that you do use, but you don't want running automatically. Some
programs will check to see if the program's own options say it should
run at Startup. If the program thinks its supposed to load at startup,
it will re-create the autorun entry.