Backup error -19 with iPhone 3G

Since the latest version of iTunes and iOS 4 I keep getting an error that iTunes cannot make a backup, the details of the error are:

2010-08-13 09:27:51.000 iTunes296:20b: restore library built Jun 4 2010 at 01:46:12
2010-08-13 09:27:51.000 iTunes296:20b: iTunes: iTunes 9.2.1
2010-08-13 09:27:52.000 iTunes296:20b: iTunes: Current software version: 8A306
2010-08-13 09:27:52.000 iTunes296:20b: iTunes: Software payload version: 8A400
2010-08-13 09:30:13.000 iTunes296:20b: iTunes: Backup error -19

Apple's support page tells me to change the settings according to this page
http://support.apple.com/kb/TS1275 under specific codes:

Error -19: The full text of this error is: "iTunes could not sync to the iPhone 'iPhone name' because an unknown error occurred (-19)". This error can occur when you attempt to update an iPhone 3G to a later version of the software and iTunes attempts to back up iPhone while it is syncing. To resolve this issue:

1. Uncheck "Automatically sync when this iPhone is connected" from the iTunes Summary tab.
2. Eject iPhone.
3. Reconnect iPhone.
4. Select Update.

Done all of this but makes no difference.
Here in Holland Apple tells me to contact T-mobile for everything iphone related and T-mobile tells me to contact Apple.

Unbelievable that a 2-year old product is now becoming defunct because of software-updates. Bad customer service on the part of Apple.
The only solution seems to be buying an iphone 4.
Something I was planning on but this experience is so frustrating that I am reconsidering. If this is what happens to 3G users after 2 years, what will happen to 4 users 2 years from now?