How much juice would my PSU have lost?

[Fredder]

I have read that due to long term usage/wear 'n tear your PSU's capacity reduces with the years. I bought an Antec Neo HE 550W in 2006. My pc runs 24/7, but nothing is overclocked.
How many watts would I have lost up until now? I want to know because I want to upgrade, but if I don't need a new PSU, I can buy a better components due to a larger budget.

Specs:

AMD 4200 Manchester S939 @ 2.2Ghz
DFI Lanparty NF4 Ultra SLi mobo
2x1Gb DDR400 RAM
1xSATAII DVD Writer
2xSATAII HDD(320 & 120gb)
XFX 8800GTS 320 Fatality Edition
2xregular 80mm fans
3xLED 80mm fans

According to some PSU calculators, I need about +/- 370W.

Upgrade Specs(CPU,mobo,RAM):

Intel E8400
2x1gb DDR2 1066 RAM
Asus P5QC
???650W PSU???

[Chevron]

You don't need a new psu. Just chillax.

[CrashHelmut]

Yeah, I'm gonna agree with Chevron. Your PSU should be fine for a while still.

But 5 80mm fans? Sheesh-ka-bob. :)

[XERXES]

Dude, nice specs.

[Frozenfireside]

It should be fine.

[Fredder]

Thanks guys, now I think it is time to do that upgrade . . .

[Chevron]

You could always use the cash you were gonna spend on a psu to get a 750GB hard drive. ;)

[Fredder]

Not a bad idea,Chevron. Didn't think about that. I have an external 750, but it is almost full . . .

[Wesley]

Yeah, I agree with Chevron, dont worry about your PSU for another year at least, the power pull of your intended PC wont drain nearly enough power to break your Antec XD And yeah, get yourself a huge hard drive with the extra cash, extra storage space is always a must.

On a side note, please tell me why you are using 80mm fans?

[Fredder]

Bought the case like that. And it works wonders, my case never goes above 40 in the summer and in winter stays between 26-30 degrees. So, I am keeping my case . . .

Oh, there are no mounting points for 120mm fans. I would have to mod the case.