Cause for a broken PSU..help needed :(

Hi,
I posted almost 3 weeks ago about putting a p2 PSU to my athlonXP since the amd's psu broke, and after exchanging the broken PSU (warranty), the new PSU broke again today

I'm really angry that this happened, and the store tells me that something like that rarely happens, maybe once every 3 years.

So what i would like to know is what do u guys think might be the cause for this.
Could it be a variation in the current? Could it be crappy PSUs ?

I thought it might be that there's a variation in the electricity current since whenever i turn on the light in one other room, the speakers make this squishy sound.

The PSU i'm(was) using is a generic 300W PSU for the following PC:
AMD athlonXP 1800+ w/ Volcano 7
Asus A7V266-E
512MB DDR 2100
Radeon 7500 Retail
SB Audigy OEM
LG CD-RW
Samsung DVD-ROM
One 7200rpm 60GB IDE HDD( Western Digital)
2 80mm Fans(one in the back, and one in the front)
1 DSL modem
1 Network card

According to my calculations(info provided from the following post: http://forum.oc-forums.com/vb/showthread.php?s=&threadid=113955 ), i need around 260-270W since i'm not and won't be overclocking, so i guess that a 300W PSU is good for me, or at most a 350W PSU.

I just remembered, i'm getting now terrible CPU/mobo temperatures since the temperature in the room is around 35C (ugghh)..when surfing the net and listening to music, temperatures r 58-60C/36-38C , and go up to 70C/40C when using a CPU intensive application(ie games). Could those temperatures have any relation with the PSU??

If u need me to post anything, just tell me
Thx in advance

PS: since i'll be changing the PSU anyways, i have the option between:
Generic 300W PSU (i think not) 0$ (since on warranty)
Enermax 300W Dual Fan 54$canadian + tax
Enermax 350W Dual Fan 69$canadian + tax
I can probably get the enermax for (price - 30) since the generic PSU costs only 30$
Sadly, these r the only options i have
And thx again for the help

As you are not overclocking, i would lower the cpu voltage on the cpu as it should work fine with a 0.1 lower and possibly for a little bit .....lower your fsb speed to say 100mhz rather than 133...underclock your cpu a bit and it will run much cooler and to see if power draw is the problem....that should help alot on power draw and should still be pretty fast until you can afford~find a good powersupply. Maybe sell your 300 watt onces you get it......and use that money plus whatever else you can afford to get a good powersupply say a antec 430 true watt PS as they are really nice...even a 350 TRUE would be ok probably and much cheaper. hope this helps

Maybe just a coinsidence , but my brother just blew a generic PSU too and it was really hot in the room. It could be a temp problem with cheap PSU, who knows

And when you say broke , what did it do when it broke? And what does it do now when you try it?

My bro's PSU just dropped dead, like someone had pull the plug and when we try to boot again , all the fans did about 1/4 rotation and stop with a weird noise.

I dunno what happened, but i kept trying to turn on the pc for 2 days from now and then, and it wouldn't, but just today morning, i woke up, pressed the power button, and it worked
I was shocked and confused, but i thought it might be a temperature thing since it's been very very hot in montreal, and the room where the computer lies is most of the time 5-6 C hotter than the other rooms

So i went to the computer store and got AS3 instead of the craptastic standard gel, and now my temps r lower by ~8C , so i'm kinda happy now.
I'm also getting the landlord( ) to get an electrician or something so he can check the wiring in those 2 rooms, and c what he can do about this current
Thx for the help