[ubuntu] Win 7 x64 HP Dual boot with Ubuntu 12.10 32bit

Hey guys, i am planning to install ubuntu on my Acer Laptop i have 320 GB space and 3GB of Ram, so i wanted to know how much space should be allocated ?

Was thinking

50GB - Win
100MB - Sys Res

25GB - /Root Part
2GB - /Swap

P.S. i dont keep my system on Hibernate.

shared - approx 200-225GB

Is this good enough ?

Thanks for your time and replies. :)