How to organize and insert blank cells between a huge number of data?

Hey guys, I am a MSc graduate, I am now working on a climate date from 1994 till 2010, they are on excel sheet with about 920,700 rows. I have the daily data for 26 weather station, each station measures about 10 parameters, but there are missing data in some days, and I need to add a blank in the missing day so we will estimate it later. Simply, the situation is like this example: You have the following data:
1
2
4
5
7
9
10
These numbers are in one column (A). I also created the standard column (B) as follow:
1
2
3
4
5
6
7
8
9
10
Now I need to put these "A" and "B" beside each other and edit column "A" according to column "B", so I will insert a blank to replace the missing data, so "B" will not change, while "A" will be like this
1
2
blank cell
4
5
blank cell
7
blank cell
9
10
Any way, attached is my example in an excel file, there 2 sheets in the file, the first sheet "Before" is the data I have plus the standard column I created, and the second sheet "After" contains the unchanged column "B" with the edited column "A" according to column "B"
My question is there any function can do this automatically for the around 1 million cell I have??? If not, is there any add IN will help?? or can I even create add IN that will do that? If nothing works, is there any office application or any other software allows me to edit my data in the way I need?? I REALLY NEED YOUR HELP GUYS!! AND ASAP!!!!
Please Note that I have at home Excel 2007 with OS windows 7 32bit and at the University I have Excel 2010 with OS windows vista 64bit.[/SIZE]

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It's a macro; use alt-F8 or alt F11, or else ask your tutor.

Hey guys, the problem was solved using the following macro:

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I found the solution in another forum, and they helped me in details, and if it is allowed I can post the name of the forum from where I've got the solution
Thanks all for your valuable inputs ))))