Synching iPhone with new computer. Will I lose anything?

I recently lost my computer whilst on holiday and have recently purchased a new one. I'm looking to connect my iPhone 4 to my new computer but I'm worried that I will lose everything which is on the phone already. When I purchase an app, for example, on my iPhone, does that need to be backed up on my computer or is the purchase saved in my account so I won't have to purchase it again? There's a section for sync purchases so do I have to do this to keep everything safe?

I think I have also reached the permitted amount of computers you're allowed to sync your iPhone with and therefore have I deauthorise one. Does anyone know if this has any affect in my content?

When you sync your iPhone onto a new computer, all the information that is on the iPhone will be backed up on the computer, it's unlikely that you will lose your data. Just make sure to read everything before you press enter.

Unfortunately, it's likely you will lose some of your content, unless you were able transfer the content from your old pc, to your new one. When you sync your iphone to a new pc, everything that is on the iphone gets replaced by content that's on the new pc. You should be able to redownload the apps for free, as once you log into your itunes account from your new pc, the apps on your iphone should automatically back up to your new pc. But music may be difficult as itunes music from one pc, doesn't automatically transfer to itunes under another pc. There's a way of getting back previously paid for downloaded itunes content, but i can't remember how. I've never been able to sync my iphone 4s to my new pc, as it tells me content on my phone will be replaced by content on the pc. I wish there was a way to back up everything on my phone to my new pc, without having to purchase an external hard drive in order to do so.