I have an iphone 3g. I just got a new computer, and don't have my old one. Do I need to do anything special before/during the sync to itunes? I don't want to lose my music or apps. I will be syncing to a PC/windows. Thanks in advance.
Well, if you haven't copied the music somewhere, then you will lose all your music. You can transfer purchases and apps before you sync and you will have those, but any music you didn't purchase from iTunes will be lost.
If you haven't updated iTunes to 9, then you can use a programs such as sharepod (it's free and there are others) to transfer the music to your computer before you restore and sync your iPhone, but these programs didn't work the last time I checked for iTunes 9 (waiting for an update).
Edit: Just checked Sharepod (http://www.getsharepod.com/download/), and it looks like the developer updated it on 9/27/09, so it should work now.