i need help with something that looks simple but i cant for the life of me work it out

In cells E10 i want to input a date e.g 01/02/12
i want the worksheet to automatically work out
what target i have hit in cell G10

my targets are
13 weeks
26 week
39 week
52 week
52+

i want the cell G10 to populate the content into one of the 5 targets based on the date i put in

so if i input

01/02/12 cell G10 should automatically have text entered "39 Week"

i also want the formula to work in all cells E10 and G10 onwards