Chad, I posted over at PT, but my wife basically cut me off from GT-5 for playing 8-10 hours straight with my online buddies and not spending any family time.(true Track Junky,

)
If you can set it up with surround sound go for it, it sounds bad ass!!
The key is car set up so make some friends and ask the faster guys about set up. I have a notebook with all my different car set ups for each particular track but that was with Prologue.
With GT-5 I used to run Nurburgring constantly. Love that track!! Very challenging.