Treadmills???

Treadmills??? I purchased a gazelle back in October and just love it. I have recently been thinking (even though I am a member of a gym my hubbys work pays for) of purchasing a treadmill and a ab lounger. I am more comfortable working out at home. I still go to the gym to tan (need to start that again, lol) and use their pool in the summer but I am happier working out here. I love to exercise now. I love using my gazelle and honestly can't wait to get my new treadmill and ab lounger. My hubby and I decided that we would take our tax refund and split it. He gets to use half on what he wants and I do. Walmart has one that is 15.0 R whatever that means. It looks nice and its under $400. What should I look for when going to purchase one? Do any of u have treadmill? Any info would be great.... Thanks Angela