As mentioned above, you can sync your contacts with one of the following three:
1) Microsoft Outlook
2) Windows Address Book
3) Yahoo! Account
I personally use Yahoo! because in doing that you do not have to keep the contacts on your machine, in the event of a computer crash. Sync up with a Yahoo! account and your usernames are always with you.
Open iTunes --> Plug in your iPhone --> Click the Info tab --> Check sync with Yahoo! --> Type in credentials.
Hoepfully that helps you out, if you need anything else just send me a PM or post a reply here.