Home PC power consumption

I'm doing some math around the power consumption advantages of thin clients, namely the Sun Ray, versus regular PCs (spell: green IT).
So I borrowed a power meter from a colleague and just checked my own PC, a fairly regular, non-game, non-graphics PC:
2 GHz Athlon, 1GB RAM, 2 HDs, Radeon 9000 on-board graphics, and the usual peripherals like Mouse, Keyboard, Speakers... nothing fancy.

Without the monitor the PC uses the following power (measured right at the power plug):

• 0W when totally switched off at the back-side
• 2,7W (!!!) when switched off only with the front side switch (or shut-down menu),
  as well as in hibernate mode
• 7W (!!!) in stand-by mode
• 115-130W when in use

I could not find a clear correlation between the power consumption and CPU or disk usage. It would just oscillate between 115 and 130W...

So - again without the Monitor - over a whole year, with my regular PC usage at home this amounts for 328kWh or about 6% of my electricity bill.