You can apply SP7 but you're already using SP7 if your BES version is 184.108.40.206. The third number is the SP you have installed. Going to 4.1 is not a service pack install. 4.1 is a whole new BES package and it's not free from RIM either. If you have TSupport it's free, if not it's a $1000 one time upgrade fee.
Double check your BES version in Add/Remove Programs. Click BlackBerry Enterprise Server and then Click Here for More Info. You will get the version there.
If you are and a version that is less then 4.0.7 then you apply SP7 as they are cummulative. Just back your DB first, always backup the DB before any upgrades.