The 240GT 512MB is a great card for the price. Very similar in performance to an 8800GT while using very little power under load and one of the lowest power consuming cards at idle.
The 1GB variant is a waste since you will run into GPU performance issues before running out of 512MB of memory.
Not to nitpick, but the hardware spec and performance of this card is a hair under a 9600GT, which is quite a bit under a 9800GT (which is exactly an 8800GT).
ew, big rebates...