excel random no. generator

[Ravenn]

hi
i'm making an excel worksheet that will generate some random numbers.
i used this formula: =RAND()*(High-Low)+Low, to generate a number between 0 and some other value and then subtract that from another number. Like this i obtain random variations around a value(just lower than the original).
However, i need these numbers to vary by a given value. (the maximum difference between consecutive values to be given by the user)
can anyone tell me if this can be done with excel(and if yes how;)) or do i have to get into VBA? If no, and i have to write code, some help would be welcome.
thank you for your time:)