summarize different workbooks data in a single workbook' sheet

Hi Guys

I do need your help regarding one of my project i do hav to summarize data from different workbook(not worksheets)(in my case 5) Through a macro to a single named summary workbook from where i cud apply graphs and other things
summary workbook should updated whnever child workbooks are updated whole data should be date based eg for april data from all 5 with their avg stored in final
sumaary wokbook do contains workbook name in one column and realted metrics in a row above them which cud interrelate

your help would be gr8ly appriciated

can data also be retrived through a closed workbook?????????
Thanks and regards
Ravinder S