If you are dual booter like me (Ubuntu & WinXP), there are a good news that you can read/store your email with your Thunderbird in a single location. On top of that, you can also share your RSS feed between both OS.
First you need to identify where you want store those data. In my case, I put it in my H drive which is in FAT32.
Then you need to know where your drive H mount point in Ubuntu. In this case, it is in /media/sda9