Nothing against PC gaming for those that enjoy it, but it's just not my thing. I've had this laptop I'm currently on for 5 years now. I'd like to play StarCraft II (my current PC can't run it), but for the moment a new PC would be an absurd luxury. I'll just keep using this laptop until it finishes falling apart on me.
For me, the big draw to console gaming is that it's a standardized format. A PS3 game will have the same performance on any PS3 it runs on, and ditto for the other platforms. On the PC, though, performance can vary wildly from setup to setup, especially once you bring driver updates into the equation. Plus, there's just a tactile and comfortable feeling to using a controller that I don't get with a keyboard and mouse.
As for the Vita, it's looking like the handheld will have a strong lineup out of the gate, though there really hasn't been any one game announced for it yet that I wouldn't just rather play on my PS3. And the way that Sony's been going with the PSP, there's a fair chance some of the games I would play on it will be ported to the PS3 eventually (like Uncharted: Golden Abyss). Right now, it's looking like I'd mainly get a Vita just to play my PSP games on a platform with more comfortable controls and Dualshock 3 support, and that's just not enough.