Index/Match to return values to compare

Help please -using excel 2010 I cannot work out how to put in place the following.

I want to enter values for various investments on different dates I.e. each column to have a date heading and each row / record to have a fund and the value for the column date. I then want to select 2 columns to compare

So my table would be something like this:

Investment. 1 jan 2012. 1 feb 2002. 1 mar 2002

Inv 1. 10,000. 12,000. 13,000
Inv 2. 1,000. 1,500. 2,000
Inv 3. 500. 600. 700


With the above I then want to select say 1 jan and 1 mar and work out the % change say in a new table or a separate worksheet. Or I may want to select 1 feb and 1 mar. How would I do this?