Thanks to all of you who have used this and given me good feedback. I've made an update based on all the comments recieved so far.

1. File copy bug fixed. Now corrects Album names with invalid characters in them, so the copy process does not crash.

2. Now copies AAC files too. Thanks to Martin for letting me know what the w800i supports AAC (.m4a files).  This does not support protected AAC (.m4p) files such as tracks purchased from the iTunes Music Store.

3. Added a Quick Launch icon.

Please download the latest version and keep the comments coming in.

Instructions:
1. Install all of the requirements.
2. Download the setup and install.
3. Start iTunes, if it is not started the program will start it for you, but be patient.
4. Select the playlist you want to synch with the phone. It is better to create a new playlist like "W800i List" and add your tracks to this.
5. Click on the Synch button to start synchronising.
6. This takes a while. You can speed up the copy process by using a Memory Stick reader, which is faster than going through the USB data cable. Take the memory stick out of the phone, put it in the reader, plug the reader in and synch.

Disclaimer: Use the program at your own risk. This program is un-supported and I will not be held for any damages, liabilities, warranties, natural disasters and if your dog eats it. However, feel free to report bugs and features.

Requirements:

.Net 2.0 Framework
iTunes 6.0 and above