I am thinking of buying a SSD for my laptop, mainly for the purpose of extended operating time when running on battery.

At the moment I use a Hitachi HTS545032B9A300 (320GB) (Datasheet) as main drive and a Seagate Momentus 5400.3 120GB as secondary drive. I dualboot Windows and Linux but I don't need the windows partition any longer, a 120GB SDD would be more than sufficient space-wise.

Speed is not an issue for me, I make heavy use of tmpfs (ramdrive) within Linux and transfers of bigger files are mainly through some network filesystem anyways, thus a cheaper SSD should do. For the purpose of comparison I chose the OCZ Vertex Plus 120GB.

Power consumption always is a big promotional thing the industry uses to make me want to buy their SSDs, some sheet on the OCZ page provides an astonishing comparison of desktop HDDS and SSDs. The numbers I got comparing my laptop HDD and their SSD were not really astonishing any longer.

Hitachi 320GB HDD: 
  Startup (W, peak, max.)     4.5
  Seek (W, avg.)              1.7
  Read / Write (W, avg.)      1.4
  Performance idle (W, avg.)  1.3
  Active idle (W, avg.)       0.8
  Low power idle (W, avg.)    0.5
  Standby (W, avg.)           0.2
  Sleep                       0.1 

OCZ 120GB SSD: 
  1.5W active
  0.3W standby

I see that there are differences, but actually they don't seem that high as I though they were. And compared to the power consuption of the rest of my system I wonder if it makes a difference at all.

Have I just taken the wrong look at the whole thing or may I be better off to buy another battery for my laptop?