Canon 28-135 IS .vs. Canon 55-250 IS !!!HELP!!!

[VibrantMindDance]

Hello. This is my very first post on OP and I'm looking for some lens advice.

I recently purchased the 40D with the 28-135 IS lens and I was considering selling it for something that can get me a little closer to the wildlife, such as the Canon 55-250 IS. The 55-250 is about $150 cheaper and I'm wondering if that is due to a significant decrease in quality. Anybody know anything about either of these two lenses? I've looked them both up on many review sites, but have failed to come to a comfortable conclusion on my own.

Any help would be wonderful! Thank you.

- SarahD