Amazon S3 Performance Issue

Recently, I got a performance trouble uploading files to Amazon S3.
Here is a brief summary of the performance results when I tried to upload a 2GB backup file of photos using my ThinkPad X61 with various conditions.

1. WindowsXP + FireFox + S3 Organizer + WiFI
   
• 2GB/12h+
2. WindowsXP + FireFox + S3 Organizer + FastEthernet
   
• 2GB/12h+
3. CentOS 5.3(x86_64) + FireFox + S3 Organizer + FastEthernet
• 2GB/20min
  

All cases above, I used the same FTTH router.

It's better to try Amazon S3 API tools such as s3sync from WindowsXP environment, but still the above difference is strange.
I'm wondering who is guilty...