Joining Data between two excel files

Hi,
I have a problem with joining data between 2 worksheets. I think vlookup can solve the problem, but have no idea how!

I have two separate excel files, I and II. Each file has around 30 columns. There are two columns from excel file I that I need to add to excel file II based on the values found in 4 columns, since the presence of these 4 values together is unique to this row.

Example:

Excel file I
A B C C D E F
5 6 7 8 0.1 0.2
1 2 3 4 0.3 0.4
2 3 4 5 0.2 0.3


Excel file II
A B C D
2 3 4 5
1 2 3 4
5 6 7 8


Any idea how this can be done. Also is there a way to use a macro instead of doing it to every file. I have around 1000 of these files!!!

Thanks!

Thanks VBA Noob,
It finally worked! I just needed to change the reference in your equation to match my condition more.

Another question. Is it possible to use a macro for this equation, such that depending on the sheets name, I would go to a certain file.

Example, if I am in sheet: Test1, I would like to search in the file named Test(1).

I hope it can work out since I have 30 worksheets and 30 files!