First off, hello to any of the Tower's former denizens. 
Having broken my D2 habit and become more mobile and substantially poorer, it hurt me badly to see the minimum hardware requirements for D3 but I went shopping anyway (online). I think I got a decent deal on a Lenovo Y570 and look forward to using it when I get to my new place. THEN I got the game and waited patiently (hah!) for the 15th, to see what my sad older Toshiba would make of it or if it would even load. Much to my surprise, it did and it even ran, though I suspect at about 4 frames per second wit the settings the game chose for me. I always played D2 hardcore but I figured a play-through as a softie was in order for this game, though now I am not so sure-maybe, just to see what is where and how beautiful the scenery is. Anyway, a soft demon hunter at four or so fps spends most of its money on repairs and (solo at least) is not going to get past Azmodan in normal, at least not at level 33. (Lots of preface but now you know the problem). If you or anyone you know is running a really substandard computer (especially a laptop), you may find that playing windowed and quite a bit less than full-screen will help. Even more of a help but nerfing the view somewhat, is switching the video from 32 bit to 16. These two changes have me running at 14 to 16 fps and my shiny new sorceress, uhhh, wizard, hit lvl 12 with no problems. She's hardcore so I don;t have great expectations for the first few times I play her but the soft demon hunter had died about 20 times before she reached 12, thanks, I think, to the video issues.
I hope this is of help to someone.

Having broken my D2 habit and become more mobile and substantially poorer, it hurt me badly to see the minimum hardware requirements for D3 but I went shopping anyway (online). I think I got a decent deal on a Lenovo Y570 and look forward to using it when I get to my new place. THEN I got the game and waited patiently (hah!) for the 15th, to see what my sad older Toshiba would make of it or if it would even load. Much to my surprise, it did and it even ran, though I suspect at about 4 frames per second wit the settings the game chose for me. I always played D2 hardcore but I figured a play-through as a softie was in order for this game, though now I am not so sure-maybe, just to see what is where and how beautiful the scenery is. Anyway, a soft demon hunter at four or so fps spends most of its money on repairs and (solo at least) is not going to get past Azmodan in normal, at least not at level 33. (Lots of preface but now you know the problem). If you or anyone you know is running a really substandard computer (especially a laptop), you may find that playing windowed and quite a bit less than full-screen will help. Even more of a help but nerfing the view somewhat, is switching the video from 32 bit to 16. These two changes have me running at 14 to 16 fps and my shiny new sorceress, uhhh, wizard, hit lvl 12 with no problems. She's hardcore so I don;t have great expectations for the first few times I play her but the soft demon hunter had died about 20 times before she reached 12, thanks, I think, to the video issues.
I hope this is of help to someone.