My phone (Sony Ericsson T630) can also store somewhere around 100 messages (i think that the SMS memory is somewhere at 1kb ... i think)
If you have a way to connect your phone with your computer (bluetooth, data cable, infrared) then you should download
floAt's Mobile Agent (works only for SE phones) where you can do various things with your phone, including downloading your SMS to the computer, so you can delete them from your phone, and have a copy on your computer.
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