well, have you checked out mandrakes site.. not for sure as i don't use mandrake and never visit their site..
the only other way i know of is to watch very carefully during install as it gives a brief description of each program its installing.. but that makes things complicated. maybe a custom install and you selecting the packages gives descriptions.
there is alot of software that these distros install which in many cases you will never need or use.
good luck, i don't know of any indexes of the software with mandrake.