Hi there
Your problem is almost cetainly down to something called Velocity scan modulation. My set was the same until I switched it off in the service menu.
The tv's setting's are the same as the 409/419, so see that thread on how to switch it off.
Only enter the menu if you are confident you know what you are doing though. To enter the service menu, you press info, menu, mute, then power whilst the tv is on standby, you have to do this quickly, and you want to turn off the SVM options to zero.
Now my set is now perfect text wise, so that should cure the problem, there could also be a focus problem with the set though, and I would get an engineer out from Samsung, to sort it for you, as they will do it, and this will not void your warranty. Once the focus and thing's are correct, don't worry, the text is razor sharp, apart from in the extreme corners.
So to sum upo, call Samsung support and get one of their engineers out.It's free under warranty, and ask them to run off the velocity modulation and then sort out the focus on the text.
Also make sure you are not in dynamic picture mode.and make sure your sharpness is turned down to about 35, and then sort out the contrast and brightness and stuff.These options are in the normal picture setting's.The tv enter's dynamic by default when you switch it on, and the setting's are ****, everything is up full.Got to custom and get all the setting's correct, and turn the sharpness right down. Then to keep these settingg's when you switch the tv off, switch it off using standby, then when you switch it off at the plug if you do that, and this way when you switch it back on, the setting's will be where you left it.