[Excel/Stata/R/?] Merging data files

#1
Several times a month I have to do the tedious task of merging data files.
Currently, I open Excel, manually remove some variables, copy a data range and paste it after another data range. This is quite annoying, because I have to scroll a lot and I have 20-30 data files each time and. In some data files I have to remove some variables/columns, in almost all data files I have to remove cases so that they don't appear multiple times in the final data set. I was wondering if somebody knows a faster solution to complete this task.

I have Excel, Access, Stata and R on my computer. Other software would also be ok, but I prefer to use the software I have.