The time has come for my hard drive upgrade. I'm considering a 320 GB or a 500 GB, not sure which size I'll bend towards because the 320 gig is VFM while the 500 gig is so tempting, size matters 
Firstly should I look at a 7200 rpm over a 5400 rpm? Does this cause vibrations, or increased vibes at all? Also how much of a loss can I expect in battery life? What performance delta can I expect?
Also will a 500 GB VS 320 GB cause further fall in battery life?
I will upgrade my RAM later on to 4 GB, so no comments on that.
Finally - Seagate, Toshiba, WD or Fujitsu - which is the best?
Help please...

Firstly should I look at a 7200 rpm over a 5400 rpm? Does this cause vibrations, or increased vibes at all? Also how much of a loss can I expect in battery life? What performance delta can I expect?
Also will a 500 GB VS 320 GB cause further fall in battery life?
I will upgrade my RAM later on to 4 GB, so no comments on that.
Finally - Seagate, Toshiba, WD or Fujitsu - which is the best?
Help please...