If one column is in one workbook and the second column is in a
different workbook, you should use a combination of MATCH/INDEX to get
your value. VLOOKUP is designed for continuous ranges.
For example, this returns the position of "abc" in column A of Sheet1
in Workbook1 located in the root of your C drive:
=MATCH("abc",'C:\[Workbook1.xls]Sheet1'!$A:$A,0)
Let's say the first "abc" occurs in row 137, then the MATCH() function
gives you 137. This formula returns the 137th value in column B of
Sheet2 in Workbook2 located in the root of your C drive:
=INDEX('C:\[Workbook2.xls]Sheet1'!$B:$B, 137)
If you replace the 137 inside the INDEX() with the MATCH() formula,
you'll get your desired result.
Hope that helps.
