I am successfully uploading my files via FTP to my server. My client is showing it is there. When I try an access the URL i get a 404. Not sure why. I entered in the correct URL (my client also offers the option to open the file)
Have you uploaded your file to the correct IIS virtual directory? I assume you are using IIS because you've tagged "windows-server-2008" to this post.
Without knowing your IIS version for sure I'm going to take a stab in the dark. If you're certain your path is correct and that your files are actually there... then my spidey senses tell me that you are uploading a file extension that's an unknown MIME type to your IIS.
If you try and host a static file that IIS doesn't have in it's list of known mime types you're going to get a 404.3 response. I've run into this with .mp4 .m4v and various other extensions. From here it's not too complicated to solve.
If you're running IIS7: http://technet.microsoft.com/en-us/library/cc725608%28WS.10%29.aspx
If you're running IIS6: http://support.microsoft.com/kb/326965
Note that you'll have to restart the app pool.