Some problem about iPhone contacts backup to computer

Hi!
My computer crashed and I had to reformat the entire system. I've lost all data, including previous iTunes library.
I'm scared to plug in my iPhone into iTunes, coz I'm unsure what it might do to it!
Here are my problem questions that I'd appreciate any help on:
- Transferring all contacts from iPhone to the computer (outlook or windows address, anything is fine...so long as I have a back-up on my PC)
- I'm confused about the term sync. Does it work both ways in transferring / backing up data when you plug in the iPhone?
- When I do manage to transfer contacts from iPhone to PC, what happens to the rest of my iPhone data in the process - photos, music, videos,apps?
Please help!
Thanks!!

You'll need to pull the music off directly -- it will wipe the media on the phone if your media library has been reset and you tell it to sync music. Easy way to do this is to pull the mp3s off the phone using iPhoneBrowser or SSH, they'll be strangely named (weird things like 0da3.mp3, etc.) but if you put them on your machine, tell iTunes to import them, and tell iTunes to organize the library by album and artist, it will automatically rename all the files back to legitimate names.

I cant get my contacts to sync to my computer. Any ideas?

If you sync the iPhone with a different computer or account - you should get a "merge" option the first time you sync your contacts.

Before playing around with this option, grab the address book database from the iPhone and back it up - that way if you end up doing the wrong thing when syncing contacts, you can restore the backed up address book database and try again.