Need to sync iPhone 4 to new laptop; don't want to setup as a new iPhone, want to keep current settings

Question

My previous Dell laptop is crashing and I have purchased a new HP g4 laptop.
I own a 160GB iPod, iPhone 4, and 32gb iPad. I am less concerned about the iPod because that is just my music.
My problem is:
How can I sync my iPhone 4 & 1st gen iPad to my new laptop without having to set it up as a new iPhone/iPad? I want to keep all my current settings as well as my groups of apps.
Any advice?
When I setup iTunes on the new computer, I had backed up all the music and iTunes folder to my external hard drive them copied from there to the new laptop. This process did not copy over my playlists (like I was told it would). iTunes is basically setup new and does not recognize that it is just on a different computer.
I set my iPod to sync and it said "was synced with other library...erase & sync?" I said yes, because it's just music. I imported each playlist 1 by 1.
Any help is appreciated; I really do not want to have to re-setup both iPhone & iPad.
Thanks you,
lavoie25

Answer 1

Thank you for the advice. I had done the backup of the whole library folder to iTunes, but I did not know I had to hold SHIFT down when opening it. I had already synced the iPod when I posted the previous message.
I ended up trying a few steps that seemed to work out in my favor.
When the iPad & iPhone were connected to iTunes, I first right clicked and chose to transfer purchases from the device to iTunes (I was not prompted by the "already associated with a library" message). Once that finished, I right clicked on the device again and chose to Back Up the device (again, not promted). Once the back up was complete, I went to each device and rechose my music,apps, movies, tv shows, books, photos and then clicked to sync. I was prompted here that the device would be erased first. I was then prompted asking if I wanted to Merge Information - I chose to merge and the sync continued.
Once the siny was finished it was as if I had finished a sync with my old laptop; all my settings and everything were in place - did not have to re-enter passwords in apps or set up mail settings again.
This worked on both my iPad and my iPhone.