Is it possible to autoformat spreadsheet like this
IF A1 = C1 then A1:E1 cells background becomes light gray
I use OO Calc, but it's ok if you know how to do it in MS Excel or Google spreadsheet
In OOo as well as in Excel, just combine an absolute reference for the column with a relative reference for the row. This way, you can copy the conditional format to every cell, and it will evaluate the values of cells A and C in the current row.
In OOo, you will have to define the conditional formatting as follows:
As result, the conditional formatting is defined for every cell selected in step 3, whith the formula pointing to cells A and C of the current row.
You should be able to do that with conditional formatting in excel, I'm not sure about the others. The exact method will depend on the version of excel.
EDIT: This should be what you need I don't have 2007 to test it though
In Excel 2007: Select range
On the Ribbon, go to the Home tab and click Conditional Formatting
Click New Rule
Click Use a Formula to Determine Which Cells to Format
For the formula, enter =A1=A3
Click the Format button.
Select a font colour to match the cell colour.
Click OK, click OK