To reach 150 FPS you will need a need a monitor with 150Hz refresh rate and I don't think there are any. If your monitor has a refresh rate of 75Hz that means you can get max of 75 FPS.
but you can get a monitor which supports 144hz refresh rate
http://www.asus.com/...s/VG248QE/
and I don't think you need to play minecraft at 150FPS to enjoy it
the cpu requirements are low a Pentium 4 cpu is recommended so you may need to upgrade your graphics card a basic card can easily handle the game you don't need to spend 300$ unless you plan to play something graphics intensive like crisis 3 or assasins creed 4.
you also haven't mentioned how much RAM you have so I can't tell what is causing the lag so check the system requirements and you decide what to upgrade most probably it might be the graphics card
http://www.game-requirements.com/?g=minecraft
http://www.game-debate.com/...=Minecraft