There are a few programs on the market that you can use to obfuscate your .net code, my question is, how easy is it for someone to get at your IP if your code is \"so called
It's easy enough for anyone determined to get your ip.
As far as "security" goes, security through obscurity is only slightly more secure than no security (which is actually more secure than bad security).
My rule has always been: Keep the Honest People Honest. Make sure you have your IP legally protected with patent applications, and have a lawyer draft up a competent Terms of Use/EULA. Use a decent obfuscator to prevent casual poking around, but realize it's not a one-shot-fix-all solution.
Unfortunately, if someone is determined to reverse engineer your code, they can do it, and they will do it.