Iphone apps .... how do I get my old 3GS apps onto my new iphone4?

Question

I am sure this has been asked many times before, but help me please because I just don't get it.
My Iphone 3GS was synched to my macbook itunes but the hard drive in my notebook failed and had to be replaced. So now with my new iphone how do I get those apps which I paid for already? When I hook up my iphone to my macbook to sync the apps, it tells me that all the apps on my new phone (which I have already placed several apps) will be erased and synced to the 3 apps on my macbook in the itunes library.
And when I go into my itunes account it lists all the apps that I have purchased, but they don't appear in the itunes app tab on my macbook, and so they won't sync. So someone in another post said to just download the app again and you won't be charged.... but I had a bad experience with that on my Ipad (downloaded an app right after I got the Ipad--> Ipad crashed (or maybe it was me) and had to restore the Ipad-> had to re-download the app and got charged for it again. Emailed apple and they said too bad but made a one time exception and credited my account. I am afraid that they will definitely not be willing to do this again).
So exactly how does this work?.... I am afraid to try to sync my new phone because it will erase the apps I already loaded and won't re-install apps already purchased.

Answer 1

By design, the iphone will sync itunes content with one computer at a time. Any attempt to sync such content with a second computer will result in ALL itunes content being first erased from your phone & then replaced with the content from the second computer. This is a design feature and cannot be overridden. Because you replaced your hard drive, your phone will see your computer as a "new" computer and all itunes content will first be deleted from your phone. The itunes content sync is one way: computer to phone. If you have photos that were synced to your phone or music ripped on your own that were not backed up, you will first have to extract them from your phone using third party software:
http://www.wideanglesoftware.com/touchcopy/index.php
Once you've done that, do the following in the order specified:
1. Disable auto sync when an ipod/iphone is connected under preferences in itunes.
2. Make sure you have one contact & one event in iCal & Address Book. The entries can be fake, doesn't matter, the important point is that these programs not be empty.
3. Connect your phone, itunes running, do not sync at this point.
4. Store>Authorize this computer.
5. File>Transfer Purchases(To make sure all purchased content on your phone will be in your itunes library).
6. Right click(Control Click) in the device pane & select reset warnings.
7. Right click again and select backup.
8. Right click again & select restore from backup, select the backup you just made. When prompted to create another backup, decline.
9. This MUST be followed by a sync to restore your itunes content, which you select from the various tabs, You'll get a popup regarding your contacts & calendars asking to merge or replace, select merge.
That's as good as it gets without a backup of your itunes library.