Poster help

I have a friend who wants me to make a poster with multiple sports shots of their child. What program will be easiest without sacrificing quality to do this? Any help greatly appreciated :)

PhotoShop any, Elements any, Paint Shop any, and Gimp. I've probably missed a few, For posters 72 DPI is used (most of the time). The editor will have to be able to work with the file size of the poster Plus the photos you copy into the work area.

Example: poster size is 24 by 36 inches, the file size formula is (color Depth X number of color channels) X width X length X DPI X DPI, at 72 dpi, and 8 bit color depth (1 word 8 to 16 bits color depth is 2 wards), 3 color channels (red Green, and Blue) and plug in the numbers 3 x 1 x 24 X 36 x 72 x72 = 13.5 meg file size at 300 DPI the file size is 243 meg

You have have free ram to run the editing program and still have free ram so it does not start using the hard disk as ram.

thanks for taking the time to help