Option 1:
http://www.feed-the-beast.com/
Option 2:
http://beta.cursevoice.com/ When using this it will ask you for the minecraft login!!!!
BROWSE FTB MODPACKS -> FTB INFINITY -> VERSIONS -> CHOOSE 1.7
When you go to play, it will take some time to actually load. Longer than it normally does. Give it time otherwise you could crash the client and have to start over. If you experience laggyness on the server, you may need to up your Memory Allotment. To do this you in the Curse program, on the upper right hand side next to your name theres a gear, click that then settings. Then go to Minecraft and the slider at the bottom slide it to where you want.
I prefer the curse voice option, it seems more stable and overall more user friendly.