Best sim card to buy in Germany

[pprao]

Hi

I am going to be in Germany for 10 days in October. I wanted to buy a sim card to put into my (officially unlocked) iPhone and use it for calls as well as 3G surfing and maybe tethering if possible.
Which company card would be best? And will it be easy to set up the internet on the phone? (APN, string etc?)

Thanks

PP