I noticed that the 460's only have ~800mb of memory. I like to do other stuff on my other monitor while I'm gaming as well.. like watch HD movies, shows etc.
Is that going to be a problem with the SLI config?
that will not be a problem at all, plus you can connect 3 monitors if you wanted :
the 480 is not a bad card, it's just not as nice as dual 460's, you can do so much more and not have to deal with the heat/power-draw.