Isn't that a 460 SE though? Don't they have less processor cores than a regular 460? Would that make it worse than a regular 460 at folding, I'm not sure but I think this might be the case.
That still being said, if you DON'T want to overclock--those cards would be fairly similar in PPD, and if you're buying 4 of them--you'll get the last GTS 450 for almost "free" (in comparison to the cost of 4x 460s). Something to consider.
If you will O/C, the 460 has a lot of O/C headroom. I'm running the cheap Palit GTX 460 (768mb) versions at 855 core(forgot what the shader is, but its linked so you can figure it out) for folding for a week now and no issues at all. They average 12k PPD each with a 2600k folding on all 8 cores in the same machine. If you get those 900 point WU's, they get about 15k PPD.
I don't know how dead set you are on that specific GTX 460, but there are definitely better deals--especially considering (I assume, since you can't QuadSLI 460s) you're doing this mainly for folding.
One way(just an example) is to use http://www.ebillme.com/ and get 10% cashback (which I think is 20% on Tuesdays if I remember correctly?) at mwave.com and buy their Palit GTX 460 (768mb) cards. They're $129 out the door, plus the cashback you would be in great shape.
I hope this helps! Always looking forward to more folding power at OCN