The most likely cause of the failure of uploading a 4.5gb file thru ftp is that the kernel dont support large files.
You will need to split the file up first then upload it in smaller chunks, if you have a linux box at home this would be easy, on a winblowz desktop, you will need to get something link winzip, but if your server is linux, it needs to support unzipping of files as well.
http://www.winzip.com/powertips.htm#split