My PC draws 300w from the wall. Is my Antec 500w Earthwatts enough?

Hey Everyone,

I just ran some tests on my PC and found that under full load (Furmark and Prime95) it never draws more than 300w from the wall (average is around 275w). I'm wondering if my Antec EA-500D power supply is enough. Here are the system specs:

i5 2500K @ 4.0Ghz
8GB (4x2GB) 1600Mhz Ripjaws
Sapphire 6950 1GB @ 875/1310mhz
120GB OCZ SSD
500GB Samsung 7200 RPM HDD
GIGABYTE GA-Z68XP-UD3 Motherboard
Cooler Master Hyper N 520 CPU Cooler
4 Case Fans (2x120mm, 2x80mm)
Antec EA-500D 500w 80+ Bronze PSU

I used 2 different tools to measure the wattage at the wall and both of them gave me the exact same results (275w-295w). I'm not sure if this is how it works but if the PSU is 80% efficient and it's pulling 300w from the wall, wouldn't it be putting out around 240w to the components in the PC? The PSU has two 22A 12v rails and says 500w continuous. Do you think that this is enough for my machine? Thanks very much!