The old Seasonic based one was absolutely kosher, atm they are transitioning from the old Seasonic design to a new Seasonic design, via CWT, atm I think it is up in the air which one you will get.
A good 650W PSU should be able to power almost any build with two GTX460s, but the Corsair TX 650 doesn't have enough PCI-E connectors.
So it will obviously be fine your build, however, it is not really what I would recommend considering what else you can get.
I'd suggest one of these:
Xigmatek NRP-PC602 600W 80Plus Bronze $60 ($20 rebate, $2 shipping)
http://www.newegg.com/Product/Product.aspx?Item=N82E16817815009
Xigmatek NRP-PC702 700W 80Plus Bronze $75 ($20 rebate, $2 shipping)
As they have higher efficiency and have reviewed quite well, and cheaper if I'm not mistaken.
http://www.hardwareheaven.com/reviews/957/pg1/xigmatek-nrp-pc602-600w-psu-review-introduction.html
http://www.hardwareheaven.com/reviews/929/pg1/xigmatek-nrp-pc702-700w-psu-review-introduction.html
http://www.kitguru.net/components/power-supplies/zardon/xigmatek-nrp-pc702-power-supply-review/
Frankly I think either one would be perfectly fine to keep for the lifetime of your build, unless you were hoping to end up with a modular power supply with even higher efficiency or something like that. If you're still set on replacing the PSU down the road then I'll have a look for something else that is even cheaper which you could use, but $40 after rebate will be hard to beat.