Create Macro in Excel 2003

I have an Excel 2003 Workbook with two spreadsheets, Monitor and Mapping. Monitor has 3 columns of data, 2 columns are fixed and 1 column updates live on the internet. We will call this CRM 1, CRM 2 and CRM 3. It also has two empty columns called VAL 1 and VAL 2. Mapping has 5 columns of data all fixed. We will call these CRP 1, CRP 2 and CRP 3, and MAP 1 and MAP 2 For each row of Monitor sheet I want to scan the Mapping sheet and if CRM 1 = CRP 1 and CRM 2 = CRP 2 and CRM 3 > = CRP 3 then VAL 1 = MAP 1 and VAL 2 = MAP 2. Scan is to be computed top down so that if different rows on Mapping meet the criteria then only the top row is selected. I want the scan to automatically refresh every 1 minute and I also want the option to have a manual refresh when I hit a button/shortcut keys.