Text messages from old iphone to iphone4

Yes. Text messages are stored in iPhone backups. Before switching to your iPhone 4, sync your old iPhone with your computer. Every tine you sync, a backup of your iPhone is created. To see these backups on iTunes on your computer, go to Edit > Preferences > Devices. After you plug your new iPhone 4 in to your computer to activate it in iTunes to work with your number, iTunes will allow you restore your iPhone 4 from the backup of your old iPhone.

http://support.apple.com/kb/ht1766

after upgrading iPhone 3G to OS4.0 or 4.01, sms text messaging DOES NOT OPEN. unless u click reply immediately as a new sms comes in. even if u restore, same problem.

apple said the new version of 4.01 would have resolved this "known issue", but they didn't

meanwhile, apple doesnt seem to care for it's old customers, but making a working phone suddenly not work properly. and u cannot downgrade to 3.xx

I'm sorry the SMS app does not work for you. My dad's 3G is running 4.0.1 and it opens fine.

Your post has nothing to do with the OP's question. The OP is getting an iPhone 4 and wants the old text messages on it.