Working in 2003, but this workbook has to also work in 2007

For this project I have to avoid macros because users are remote and may not
enable macros.

I have a column which needs two different data validation criteria;

(1) ColumnA Column B and ColumnA <Column C (I can do this with data
validation)

(2) ColumnA does not contain values at more than one decimal place
4.2 is ok, 4.21 is not
I can also do this with data validation (custom formula)

However, Excel appears limited in that I cannot apply more than one data
validation criteria. Is there any (non-VBA) workaround, or am hosed? I'm
considering the use of conditional formatting, but again this only provides a
visual prompt, and does not force the value to meet validation standards, and
unlike the data validation, there is no prompt to tell the user why the value
is inappropriate.

I tried setting up a mirror cell (D1=A1) and set the secondary data
validation criteria on D1, but changes in values passed via formula do not
appear to trigger the data validation check.

Thank you for any suggestions,
Keith