VRBO and Cyberrentals are both part of the Homeaway network but I agree that Cyberrentals is more user friendly.
We like to stay in Kissimmee but as Heather C says there isn't really a bad area - look for a gated community/resort and check the distances to the various parks you want to visit. The area will most likely depend on how far you want to drive each day
Oh, and I meant to mention that www.thedibb.co.uk/villa-map.php offers a great view of where the different neighborhoods are in the WDW area. Good luck!
If you go to the home page for homeaway.com which vrbo and cyberrentals are a part of there's a homeaway guarantee page. http://guarantee.homeaway.com/ Look across the top of the page for companies that are part of the homeaway family.
You can register your rental with them and if it's not legit you get compensated.
You can also check out the tax records of the owner when you find out their name on the Osceola Country ( or other county) website. http://www.property-appraiser.org/ Just do a search using their name.
Good luck.