Do you crate your dog when you're at work, or let them roam free?

I have a dog that's a little over a year old, and we've had her for about four months (chihuahua/terrier mix - about 6 lbs). She was already housebroken when we got her, but she does have little accidents every now and then (I still think it's because she's fairly new to our home), so we keep her crated during the day while at work. Some people have told me that it's cruel to keep a dog crated, and that we should let her roam free in our apartment all day while we're at work, or at least confine her to one room. What's your opinion on this? I would be extremely hesitant to let her roam free, especially if there's a chance of an accident. I do feel feel bad when I leave her, and we've recently had to take out her bed while we're gone and replace it with fleece blankets because she tears them to shreds. But I feel that she needs to be crated for her own good. Also, she sleeps in her crate at night - she's trained to do so.