Search forums... There are douzens of threads about this already which explain and give links... (
Do not use MSConfig for this!)...
Start-up Programs
How do you stop things from automatcly apearing when turn on your PC
CookieRevised's reply to Removing items from "msconfig"
etc
etc
If you want the best program there is (most complete!!!, absolute free, no installation required, just 1 file), use
AutoRuns. There is no other alternative which can even tip AutoRuns.
PS: a program to monitor what is being added to the RUN registry keys is
StartupMonitor. It will pop up asking you if you want to allow the program being added. Extremely usefull...