Data From current week plus 3 weeks in one column and have it update as the week progress

[jampb]

Hello there! I am new to the forum so hope someone out there can resolve my issue:

I have data from every week starting from Mon,Jan7,2013 to end of the year per item. I need a sum of 4 weeks starting from this week. Then, next week, I will need sum of the 4 weeks starting Mon. July1, 2013 plus next 3 weeks and so on. The data will show up in one column on another worksheet2.



Datasheet 1:
A B C D E F G
ITEMS 6/24/13 7/1/13 7/8/13 7/15/13 7/22/13 7/29/13
1 50 5000 4502 40 454 45
2 20 5405 4040 7458 78045 452
3 9 45054 405 532 7878 124
4 8 45 405 7405 45 12
5 100 450 4 574 78 12
6 1000 4502 452 705 75 7

Worksheet 2 where the calculation needs to be stored:
Total 4 weeks (sum of column B, C, D, E)
9592
16923
46000
7863
1128
6659

What I need is a formula that will automatically repopulate by recognizing the current week and add 3 weeks.
So when I open the worksheet on July1,2013, I should see the sum of data for weeks starting, 7/1/13 7/8/13 7/15/13 7/22/13
When I open the worksheet on July 8th or 9th even, I should see the sum of data for weeks 7/8/13 7/15/13 7/22/13 7/29/13


I hope this makes sense! Thanks