lord . . . there's been quite a lot of dribble here
my take on it - i7 allows for more simultaneous threads . . . is this better for gaming than a quad that only allows for a total of 4 threads?
depends on the game.
Some games don't have a thread cap, some work with only 2 or 3 threads. Average is 2, ATM. Will we see more and more games that support more CPU threads? yes, that's a definite.
But, as much as has been pointed out, a new CPU architecture can lead to drastic differences over current tech - not so much in FPS, but more in how quick the whole system runs . . . this will reduce load times (read: less stuttering), will reduce avearage min FPS, increase average max FPS, and can also eliminate background OS processes (because, really, as much as it's a smart idea to disable all AV software, and other unnecessary OS processes for gaming - how many do? Also, how many processes that are unnecessary for gaming are critical for OS operation? Plus, it's a hassel to kill these services at times).
Secondly - for as many reviews that are out there already - games that are heavily GPU dependant will show very little, to no increase with a new, better, CPU. Falling into this category: Crysis, CoD4, FC2, STALKER: CS, etc . . . why these games are used for benchmarking a new CPU is beyond me, as, IMO, it's pointless. You'll see a bigger performance increase by switching to a new GPU for these games, than you would a new CPU. But, all the review junkies and hardware-kiddies are all about these games, so I doubt we'll see those removed from the benchmark suites any time soon . . .
DDR3? Well, sure the run-o-tha-mill DDR2 is dirt cheap, but if you intend to do any OCing . . . you know better. DDR3 has come down drastically in price over the year, and there are still many sweet deals out there, too - besides, DDR3 performs as well, if not better, than a lot of upper-end DDR2 does.
I made the switch to DDR3 early this year, and personally, I don't intend to go back. Even at it's stock speeds - the bandwidth it's capable of has speed up overall system times immensly - programs open and run quicker, there is less stuttering in games, reduced waiting on SYS intensive programs, etc. For some reason, this arguement rarley comes up when people start debating DDR2 vs DDR3.
As to the OP - no, ATM it's not worth switching over to an i7. Boards will be expensive, the new CPU is expensive . . . if you don't already have DDR3, that's another expense - possibly another PSU needed . . .
and there still might be some issues with first production CPUs as well - wait a while, not only for overall hardware prices to come down, but for hardware manufacturers to iron out the quirks and kinks in the new CPU architecture, the new X58 chipset, their motherboards and BIOS control, heat issues, etc.