Double Condition, Or Else

Have a quick one, trying to figure out a simple expenses/income/saving tracking table for my wife and in-laws; have figured out most of it. Will use pivot to extract most of the data, but on a summary sheet I need double condition sums (or at least I guess so...). For example I have "amount" column (which is expanditure) and date column (have used function to extract month and year for other purposes to separate columns), how can I calculate multiple costs (all the costs/expenditures in a month) that have taken place in eg. april 2008 only/ since I want to display it on a separate sheet as a summary overview...here's the link to imageshack, dunno if it's gonna work:

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Have tried something like: =SUMPRODUCT(month="4")+SUM(amount) but it sums up the entire column...

or this one: =SUMPRODUCT(ISNUMBER(MATCH(4,month,0)+SUM(amount)))
I know I miss a bunch on the last one