Well for one, fonts. Make it look better, I don't know how, I'm no designer, but it looks like it's been done by a programmer. It's ok, but it can be gorgeous! Also perhaps underline the search results. It should be clearer what is clickable and what not.
Also the background going green on hover isn't looking good I think.
You can change all that stuff in the settings; if you come up with a set you think looks better, I'd love to investigate.
As for font, what browser/OS are you on? It is using Segoe UI as the main font, but sadly this isn't installed on all computers. The backup is Arial, which I agree could be better.
I quickly did this with Stylebot for Chromium: http://min.us/iErKG.png :) I'm sure other readers of this thread can come up with something much nicer. Perhaps you should offer a challenge for who can make the best one.
But I already prefer this css to the original. I think I'll keep it.
Also the background going green on hover isn't looking good I think.