I am using onboard sound, but it isn't worth it to me to use a sound card.
I have tried DX9
I have gone to Nvidia site already to update drivers
Overclocking actually slows down a duel or quad core computer, so there would be no reason for me to do it in the first place
No idea what the BIOS is for, so if you elaborate I'll try.
ok, I did the stability test. The benchmark was 468, Ill get back to you guys about what happens after a half hour of the test.

Keep in mind that both of the games you've mentioned (Fallout 3 and CoD 4) have reported crash issues.
That goes especially for Fallout 3, which is a crashing nightmare on some systems (mine for example). Try playing around with advanced in-game visual options also, mainly turning off the fancy stuff.

Ok, I would go in to the Nvidia controls and select performance over quality.
Run MSCONFIG and load a limited set of drivers
Don't use AA and select medium or low graphic settings on the games
The BIOS is entered during boot , you will need to search for Dell's key to use to enter the BIOS. Most use ESC or one of the F# key
I am leaning towards a heat issue

Its a heating issue, I'm almost positive, when we bought the card, the built-in fan was loose, we brought it in and they said it was fine, I didn't think so.
When I ran the test lukas told me around 25 minutes into it it crashed, but my sisters computer (running an 8600 GT) was fine for half an hour.
I think I plan on upgrading my card anyway. Might as well take this as a bad experience.
Oh stone, it crashed also on Sims 3 CoD5 R6V2 and if I turn the graphics up, L4D

This is an odd question, but do you smell anything burning coming from the card when you are using it? Are you using a surge protector with grounded outlets? It sounds like your card is defective. If you can return it to the store. If they say it's fine, tell them you just want an exchange or your money back then go somewhere else. If not try and RMA it with the vendor or Nvidia. You should be able to get a replacement without having to buy a new one. Just say that you are using official drivers and the the card is hot to the touch or you smell a burning smell coming from the card and a black screen when you play any new game. Don't say that you used Rivatuner or anything else because then they'll say it's your fault or a driver/OS problem. If they push it, say the the fan appears loose, and if they have you tighten it, say it does the same thing. If you have a CC you come sometimes get an advanced replacement where they ship 1st and then you just put the old card in a box and ship it back. In many cases you will get a return packing slip. I hope this helps.

Best buy said they "should" be able to get me store credit, fingers crossed.

If they don't speak with a manager, and be firm about the store credit. Good Luck!

I find it hard to get treated well at stores with support issues, mostly because I'm 14. Secondly because I bought the card in December of 08. Something tells me the manager wont give me the time of day.

Also worth checking out your power supply, if the card isn't getting enough juice it can cause problems.
I currently have a cheap dell box, which comes with a barely competent PSU, so I can't upgrade because any modern cards would require more power than I have.

We upgraded power when we upgraded cards.

They may do it, but they will try to talk you out of it. Bestbuy has some of the worst customer service as they only see customers as dollar signs.

Hey sk8ing - this has absolutely nothing to do with the issues you're experiencing at the moment, but you might want to consider trying the 64-bit version of Vista in the future.
You may have noticed it already when looking at the above numbers, but Vista 32-bit can only deal with 4GB of memory at a time (same with XP).
Because your video card is using 1.5GB of memory, your OS only has enough room to deal with 2.5GB of your RAM, even though you've got 4GB installed.
If you put in a 64-bit operating system, this limitation goes away, so you'll have all 4GB of RAM available to you, as well as the 1.5GB of video memory.
Best of luck getting your refund!

Bestbuy now says that they MAY refund my money, but if they don't I have to pay $70 for Geek Squad to do a diagnostic, and if it shows that the card isn't functioning properly they will give me one free. If it is working I have to pay another $200 to have them fix the card, so I would be paying $270 to fix a $250 card, I think if they run diagnostics and they want to charge me more, I'll just upgrade cards from TigerDirect and be done with best buy.
Ok, I just talked to PNY, thank god I'm still under warranty.
I think the card is overheating due to a factory defect in the card. I opened up the case for better ventilation and played a game, and the card stayed cool longer, but eventually overheated and crashed. I think I'll just return it and hope I have better luck with another card.

I hope your new card works. Good luck with Pny.