lucy24 - 10:19 pm on Dec 15, 2012 (gmt 0)

Cold-blooded answer:

Does registering one domain name give you control over all similar domain names? There are people out there who make a tidy living simply by snapping up any name that's similar to an established domain name, and then selling it to you at an inflated price just so you can make sure nobody else gets it.

Your position is still weaker if your company name isn't a registered trademark. (In the US, "trademark" and "registered trademark" are very different animals. You can look it up at uspto dot gov.)