Kon, your present setup shows 32 bit Cubase install, you will be able to access more of your memory using the 64bit version, BUT if you are using 32 bit plugins and change to 64bit Cubase, you open up a new issue of getting your 32 bit plugs working with 64 bit Cubase. TShepo may be correct that 5.5 is more stable, but for you his suggestion of the 64bit version may not be the best choice for you.