Car Buying for this Dummy

I was getting an oil change the other morning when the grease jockey beneath the car noted that I have a small transmission leak, he thought, though it could be just water splashed up on it. Well, being the worrier I tend to be, it seems like now would be a good time to turn in old faithful for something new. I've pondered this for a long while. My car is a 1997 Honda Civic and it's had a good run, turning over 150,000 miles just this past weekend. However, I despise the haggling of buying a new car.

I need any advice you wish to give a guy in my situation. I am looking at either another Honda Civic or a Toyota Corolla, though a friend just showed me a Scion Xa, which looked kinda cool. I'm all about reliability and gas mileage. Any opinions? Do any of you own one and can share experiences? Any advice on handling salesmen and haggling?

HELP HELP HELP!