umm...ur fone has a microSD expandable memory slot, right? tried saving the txt msgs to that, and from there transferring them to the PC? (i'm assuming the fone came with some software like Nokia does with PC Suite to transfer stuff or backup the memory onto the PC)
If you'd have a Nokia phone you could simply upload the messages in a bulk operation by using the Nokia PC Suite. I don't know if Samsung has something similar.
If you're with o2 then they give you this Bluebook service which allows you to sms ur text/picture messages and anything else from your phone, up to ur virtual 'Bluebook' for no cost! Then you can access them anytime and the storage space is 1000Mb :D