Excel help (again)

["cwest" <cwest@xxxxxxxxxxxx>]

I have a file of values and dates with different numbers of days between
dates. In Excel, what's a reasonable way to measure the distance of each
value from a line of best fit so that I can categorize outliers. I'd
like to be able to say that certain outliers are more or less
(in)significant. 

I played with the LINEST function in Excel but I can't get the hang of
it, and I couldn't see how I could plot a regression line. 

Appreciate any ideas or help

Thanks in advance
Colin West