I have constructed many interlinking excel based spreadsheets which have
numerous functionality through a series of macros I have written.

I realise that a lot of the calculation in the spreadsheet can be
altered/tampered with. Is there some system/software where I can have the
calculations in the background and just display the results so the
calculations cannot be tampered with and the new inputs can be easly entered?

Please note the only programming experience I have is with excel VBA, so I
doubt I wil be able to cope with any really complicated programming languages
(C++ etc).

For the meantime I have protected the cells/worksheets where possible.

Can anyone offer me any suggestions of how I can improve my systems?