My present system uses a Zalman MFC2 and on average in idle it reads 220 watts, underload its around 375 watts.
 
MSI 790FX socket +AM2
FX-62 @3.4ghz
thermaltake blue orb II HSF
3GB of OCZ PC 6400  
[2] 15k rpm SAS HDD's
Lsi Logic SAS card
Ht omega striker sound card
[2] Hd3870's in crossfire
DVD+RW
front card reader w/FDD
in an Antec 900 w/
    [3] 120mm fans on low
    [1] 200mm fan on high
 
all this is on a Silverstone Strider series 850 watt PSU
 
according to the PSU 2.5v lite calculator it says my system would need at least a 537 watt PSU,
 
but according to my Zalman MFC2, it shows much much lower readings...
 
I will be building a new system, i want to use a S12 380watt PSU based on the wolfdale's and for future builds is there some sort of meter [multimeter], that i could use to accurately tell me what my PC is using or maybe some sort of software, or maybe bios option?
 
Is there something I can use to tell what my wattages w/o a $70 Zalman MFC2 unit? Like is there a stand alone unit, not looking to spend a whole lot, maybe 30-45 bucks? I would like an accurate reading +/- 10 watts.. is there such a device?

     The readings you got sound accurate, the 220 watts is idle, and the 375 watts is on load for a few components.  The PSU calculators are usually running off of 80%-100% TOTAL system load.  You most likely will never reach that with a PC.

How about a $49 zalman MFC2
 
http://www.newegg.com/Product/Prod [...] 6811999174
 
Mine reads 223 now and about 410 in crysis    
 
E6750 @ 3.4
zalman 9700
asus p5n-d 750i mother board
2x 8800 gts 512
2x 320gb hdd sata
dvd+rw drive
antec 900
3 120mm on low
1 200mm on low
750 w psu  

Get you self a cheap Wattmeter from your next diy shop. You know the one you plug in between your outlet and PC... And anyhow; why do you worry? You system does not use the full power of the PSU; be glad about it...

kill a watt or seasonic power angel should get the job done, the power reading from zalmans seems right. my machine draw 120 watt idle, 220 watt on loading, x3210 3.4GHZ and 8800gts 640 MB. 2Gb ram 2sata HD

ty for all the info guys, the kill a watt seems to be cheaper at only $25 sphipped vs. the seasonic power angel at $40. i cant really see any differences between the two they both claim to do the same things, I"ll go with a kill a watt, ty guys.
 
P.S. now all i need to do is figure out the difference between the Kill a watt 4400 and the kill a watt 4460 EZ...?

I have a cyberpower 1500 VA UPS with a similar power meter running my system, i idle at 170-180w on my system, but running prime 95 and 3dmark at the same time takes it up to 348w peak with just one video card x1950 pro in. + my sig.

yeah but the hd3870 is much more power effecient than the x1950 pro