How Much power per month do I consume?

Looking at my system specs below (note the Antec TrueControll 550W PSU), how much electric do you think I consume per month by leaving my computer running 24/7 at full power (no hibernate or system standby or hd power down) ?

I am moving out to an apartment and I need to get a good idea for about how much money per month my PC alone is going to cost me to run 24/7? I need to run it constantly because I run file servers off of my PC.

I also have another pc but that is only a p3 850mhz with a 300 watt PSU.. so I don't know how much that will cost either to run 24/7 ??

If you could give me some useful numbers here I would appreciate it very much. This way I can determine what I can do about my power options.

Also, IF it was to expensive to run my pc's 24/7, is there a low power mode option that I can use that will still let me FTP into my computer when it is in low power mode (like it will wake the computer up when I try to connect to it remotely)? I use the onboard Lan on my abit motherboard and I have a cable modem connection behind a router if that matters.

Thanks in advance!

NEW SYSTEM:
P4 2.8c (800fsb), Abit IS7, Kingston HyperX PC3500 (2 x 512mb), IBM Deskstar (60 gig @ 7200rpm)
OLDER SYSTEM:
P3 850mhz (100fsb), Asus CUV4X, 620mb Micron PC133, WD 40gig 7200rpm

Well I read the question, but its really impossible to guess how much power a particular system is going to use. My only suggestion would be to meter the power consumption of the PC's somehow, but I have been unable to find some sort of handheld meter he might use. And I assume from his previous post that he doesn't pay his own electric right now, so it seems unlikely that there would be an external electric meter for his particular apartment. However if there is, that would be the way to find an answer. Turn everything in the apt. off, see how much power is being consumed, then turn on the PC's and measure the difference.

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Armadillo<font color=orange>[</font color=orange><font color=green>TcC</font color=green><font color=orange>]</font color=orange> at Lanwar and MML

My point is that its really a question of load. You can't simply take average figures for each individual component and add them together and expect to come up with any kind of meaningful figure. As the first paragraph in your link says:

"A 400-watt switching power supply will not necessarily use more power than a 250-watt supply."

The same principle holds true for just about any component you can think of in the PC. For example a HD being accessed constantly will draw more power than one that is simply spinning, a CPU that is idle will use less power than one that is active, etc. So without knowing what kind of load the PC will be putting on the PSU, which is pretty much impossible to guess, you don't know how much power it will be drawing. Unless you can meter it, you're just making stabs in the dark.

<font color=white><b>_________________________________________________</font color=white></b>
Armadillo<font color=orange>[</font color=orange><font color=green>TcC</font color=green><font color=orange>]</font color=orange> at Lanwar and MML