Application for Magento products import from Excel Spreadsheet

My? site is in a mySQL database, running php and is located at? <[login to view URL]>. I need? an expert in? migrating? products from an Excel spreadsheet? into? my Magento installation in order to populate our website with products from one vendor. We would like to have a program? written that will allow us to import/syncronize? product information and inventory levels whenever we want using? Excel spreadsheets like the one that is attached. Please note:? ? I need 252 configurable products entered.? They have a lot of variations, so the total simple products will be about 24,000. What I am looking for is? to have the information that is on the spreadsheet imported to my site as configureable products.? I would like for the sku's to read like this: style-color-size or 10001A-ABL-XS.? I do not need the UPC column uploaded at all.? ? Then? I would like to be able to update the stock levels (Quantity) of these products whenever I choose using an application.