Yeah you're right, The dell XT with capacitive touch was released in december of 2007 with a capacitive screen, the iPhone was released on june of 2007, I thought the op meant the iPad.
Well I did have a capacitive touch screen "tablet PC" (Panasonic Toughbook). But that's pretty much irrelevant since the UI didn't have pinches and swipes and wasn't designed primarily for use with fingers.
There still were Tablet PCs with capacitive display before though, for example the ThinkPad X60 Tablet had an optional MultiTouch display and it came out in 2006.