Is it a correct sentence?

Shiner   Fri May 12, 2006 11:23 pm GMT
Please do tell me if following sentence is correct or correct it if it is not. Thanks
"I said what I thought was best."
Jim C, York   Fri May 12, 2006 11:36 pm GMT
Yeah that is ok.
Shiner   Fri May 12, 2006 11:40 pm GMT
Thanks Jim :D
j   Sat May 13, 2006 9:25 pm GMT
Jim C, York: "that is ok."
BTW, I always wonder what's the difference between "that's ok" and "it's ok".Are they are interchangeable?