So what is a good ENB mod my card can handle?

ENB preference changes with each one player, with what the player want his/her game to be, what your his/her mood is in the day. If your system can handle, let me point some I tested:

Full of colors? http://skyrim.nexusmods.com/mods/30158, or http://skyrim.nexusmods.com/mods/21123 (my actual preference), http://skyrim.nexusmods.com/mods/21223, http://skyrim.nexusmods.com/mods/33268 (new and very good, i can change to it when i change again)as lots of others.

Cinematic or Realistic like life? http://skyrim.nexusmods.com/mods/24235, http://skyrim.nexusmods.com/mods/30406, http://skyrim.nexusmods.com/mods/22056, etc. (mostly enbs goes for real like life and darker shadows).

Want to quick test different variants? http://skyrim.nexusmods.com/mods/23765(have various presets in it, none lose to others, and is fairly light to your system).

Also going to http://enbseries.enbdev.com/forum/viewtopic.php?f=14&t=17&start=9110 home page you can see what people and enb developers have acomplished, and make your mind just looking at screenshots (hundreds of shots to make you drool, lol).

Also remember that you can tweak yourself any of the presets. The guide that comes with skyrealism helps a lot with your learning.