I used to use FileZilla to transfer files between my iPhone and computer. It works well with smaller files. I was trying to copy some huge movie files from my computer to my iPhone and the estimated time is several hours! One reader has suggested a program called DiskAid, but I have not tried it yet. I think it’s a good idea to try it out.
The web site is here. Both Windows and Mac OS X versions are provided. You also need to install iTunes in order for the program to work.
Once installed, you can run it before you connect your iPhone to the computer. You cannot drag and drop files from Windows Explorer or Finder to it. Everything is done through the program. You cannot select multiple files at the same time, but you can select a folder. The transfer speed is fast compared to the file transfer via wireless connection.
For version 1.5, the default location on the iPhone is the /var/mobile/Media . If you want to access other location, use the selection box on the lower left corner to switch. Note that you have access to some of the system files now. Be careful about deleting files you are not familiar with, you might render your iPhone useless.