There is a sim import option on the iphone. You go there, it has you put the old sim in, it sucks the contacts in.
What ever you do don’t let it sync with gmail. I never realized gmail puts every person you’ve ever emailed or replied to into your contacts. I ended up with 100’s of contacts I’ve never even heard of.
Easy way to mass delete them if you do fuck up like I did… create a blank set of contacts in outlook express and have the iphone import those.