Why Does My Computer Keep Turning Off In The Middle Of A Online Game?

I just finished building a new gaming computer.
A8N-E Asus Motherboard
Biostar Egate GeForce 6600GT PCI-E video card
AMD Athlon 64 Processor 3800+ 939
Linksys wireless-G PCI adapter with speedbooster network card
Windows XP Professional x64 Edition
Seagate 320G SATA hard drive
52x CD SATA driver
Antec Neo HE 500w power suply
I have installed all up-to-date drivers. The only driver in question is the network card. I could only find one that would work. I start playing any online game though and it plays great for about 5-10 min. then computer just shuts down in the middle of the game. Sometimes it turns back on by itself after a few seconds. Other times I have to turn it back on myself. Never got any error message or anything after turning it back on though. One time even punched desk after about 5 minutes of it shutting off on me and it just turned back on itself. Check power connections in and out of computer can not find any bad.
Can anyone help me?

I’m Christian, He’s Muslim… I’m An American Citizen, He’s From The Middle East…?

We couldn’t be more opposite.
We met online just the other night, but I can’t get him out of my head. We’ve also spoken over the phone.
He moved to my state about a month ago. Our cities are about an hour apart.
I’ve already told him I prefer Christian guys and have a habit of trying to convert any non-Christian guys I go out with– my pastor refers to it as “Missionary-Dating” (seeing dates as converts and being a Missionary instead of just a date or a girlfriend).
He’s looking to find a woman, marry her and start a HUGE family right away (at least 6 kids). He has no intentions of returning home, but will continue to send money to his family. I’ve already considered the possibility that he’s just looking for a green card or an insurance policy (a baby).
I know I should just consider him a friend, but I think I’m falling for him. It also doesn’t help that my favorite Disney movie is Aladdin…
Should I keep him at a distance or follow my heart and let things just happen?