Display Drivers (I assume) constantly crashing during games.

Hello, there, everyone. First of all, here are my specs:

Operating System: Windows Vista™ Home Premium (6.0, Build 6002) Service Pack 2 (6002.vistasp2_gdr.110617-0336)
Language: English (Regional Setting: English)
System Manufacturer: Gateway
System Model: FX4710-UB003A
BIOS: Phoenix - AwardBIOS v6.00PG
Processor: Intel(R) Core(TM)2 Quad CPU Q9300 @ 2.50GHz (4 CPUs), ~2.5GHz
Memory: 6142MB RAM
Page File: 1962MB used, 10466MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
Card name: NVIDIA GeForce 9800 GT
Manufacturer: NVIDIA
Chip type: GeForce 9800 GT
DAC type: Integrated RAMDAC
Display Memory: 3306 MB
Dedicated Memory: 491 MB
Shared Memory: 2815 MB
Current Mode: 1440 x 900 (32 bit) (75Hz)
Monitor: Generic PnP Monitor
Driver Name: nvd3dumx.dll,nvwgf2umx.dll,nvwgf2umx.dll,nvd3dum,nvwgf2um,nvwgf2um
Driver Version: 8.17.0012.8026 (English)
DDI Version: 10
BGRA Supported: Yes
Driver Attributes: Final Retail
Driver Date/Size: 8/3/2011 07:50:00, 15064168 bytes

I have an issue that spontaneously popped up about three months ago. My driver fails, CONSTANTLY, I assume. I say I assume, because I never get an error message. Whenever this happens, which is always during a game, it freezes my computer to the degree that I almost always have to force shutdown the whole thing.

What's specifically happening is this: I'll be playing a game, almost any game, really, and do something in the game that involves a command, like interacting with something in the gameworld. BAM. The screen goes black, and the audio freezes and starts skipping. Once in a long while, it'll come back after a moment. Most of the time, the screen either just stays black, with the skipping audio running in a permanent loop, or the audio stops and the screen begins blinking on and off, seemingly trying to restart the drivers over and over again. In some games, like Saints Row 2 and Fallout: New Vegas, it doesn't happen all the time. Sometimes, I can play for hours without an issue. But for most games, most notably Batman: Arkham Asylum and Borderlands, it happens constantly, to the point the games are functionally unplayable.

This is immensely frustrating, since it seems to occur even when the games are running at maximum settings smooth-as-silk. Also, the computer was barely used for the better part of a year and a half, so the card has only been in frequent use for less than two years (the computer was originally purchased in October 2008).

Any help would be greatly, greatly appreciated!

Please note: the innards of the computer have been untouched since purchase with one exception: the DVD-rom drive had to be replaced in 2009 due to hardware failure that appeared to be a manufacturing problem. The graphics card is stock.