Thanks for your opinions everyone. I went to test drive both the SLK55 AMG and the 135i over the past few days.
The SLK55 turned out to be very fast, but just not my thing. It was just... well... boring. Beautiful car though. The 135i was extremely fun to drive. I'd write a review, but I really don't have the time right now.
In the end, I ordered my 2009 BMW 135i with a 6 speed manual. It should be here in about 8 weeks. Alpine White with black interior, gray poplar wood, cold weather package, sport package, and the upgraded hi-fi stereo system.