Worth getting the new Air?

I have a 2009 MacBook Pro, 17", 2.93Ghz Core2Duo with 8Gb RAM. It's been a good machine the last couple years, though the battery only gets about 4 hours if I'm lucky now, but that's to be expected. I'm just looking for something a little lighter(this 17" is a pain to carry sometimes), but I just want to make sure I'm not giving up performance. I'm pretty sure any new mac is going to be faster than what I have, so this might just be a silly question, but I just wanted a second opinion. Would the 11" MacBook Air with the i5 and 4GB of RAM be faster or as fast then the mac I already have? I appreciate any replies

Might want to take a look at GeekBench. I did a quick search and the points are in favor of the new MBA.