No I was afraid that would blank out my phone as I have nothing in my Cal/Contacts on my Laptop. I didn't want to override my phone with nothing. Guess I can try though....fingers crossed!
It should work. If you're concerned, make sure your iPhone takes a backup through iTunes before you do it. I had made all my calendars that were on my iPhone on my iMac, and when I started syncing it to my Windows PC, it just backed them up. Later when I installed Outlook for Windows, I turned on syncing and it put the contacts and calendars into Outlook.