Upgrade from 3G to 4 help

[mcwbyu82]

Hey All,
Had my 3G for almost 2 years and expecting my iphone 4 tomorrow.
The 3G was my first iphone so I havent gone through the upgrade process yet and I must admit I have probably only synched my 3G 3-4 times.
I am sure I could piece togther the correct process for a smooth upgrade but thought I would just ask for a quick response.

So what are the exact steps I should take regarding back up and then restore?
Should I download/install IOS4 on my 3g first?
Thanks

 

[codenamecueball]

Sync phone, let it backup, then when iPhone 4 comes, choose restore from backup blah not new iphone

 

[-FlyAuburn-]

Sync phone, let it backup, then when iPhone 4 comes, choose restore from backup blah not new iphone

What if you are restoring from a 3.1.3 backup to an iPhone 4. Won't that mess things up? Also, what do you do later (I have a new iMac on order) if you want to sync to a new computer? Will it copy all files on the phone to the new Mac and automatically de-authorize the old computer?