C# on IIS Import of xlarge XML files .1-500mb + JPG images

I have project where I need to import property data from XML feeds FTPd from an in-house server. The XML feeds come in zip files, which need to be unpacked and also contain JPG images relevant to the property data. The zip file size can be small to huge. Eg for the regular 15min updates the zip would be 1-2meg including images. The XML files would be 10-20kbs each. When a full push of data is created the file size of the XML balloons out to well over 500mb (Just the XML) as there are 1000s of properties. I require the XML file data to be inserted into a MSSQL Server DB, into 2 main tables residential_ & commercial_, along with 2 other tables resimages_ & commimages_ which will insert all the image file names and details. The XML data is broken up into 3 parts, Res, Comm and Land, but I will supply the latest technical doc on the XML file structure. It would obviously need to Insert or Update if the record is currently in the MSSQL db. There also needs to be a check in place that XML files are not currently being uploaded before the script is actioned on the file to avoid cutting the file off and stopping the upload. The website is hosted on latest IIS running Coldfusion 8 front end and custom CMS. I require the all the images to be copied to a location in seperate propertyID folders as there are over 25,000 active images. This location also needs to be inserted with the image data. While i'm not too familiar with machine code and C#, i've been told this is a great way import massive files like the XML at a fraction of the time it takes with CF or PHP etc. CF and PHP actually timeout when the file size reaches approx 3meg trying to import the XML. If you require more information on the project to quote this kind of thing or would like to discuss, let me know. Thanks.