Constant BlueScreen crashes -- driver issue?

I think I may have a driver issue, but I'm at a loss as how to fix it. My
system specs: Vista Home Basic 64-bit, 2 GB RAM, GeForce 8600 GT (driver:
162.22_forceware_winvista_64bit_english_whql), X-Fi XtremeGamer (driver:
SBXF_PCDVT_LB_2_15_0002), Gigabyte 965G-DS3 motherboard.

I've been getting BlueScreen crashes since I bought the machine. They seem
much worse now, hours or minutes apart. The most common seems to be with a
Stop 109 error code. I've also seen C1, A, 3B, 4E, 24, 1A, and probably some
others I can't recall.

I have all the latest drivers I can find and all the Windows Updates that
seem applicable. I've completely uninstalled/re-installed sound and video
drivers several times to no effect. I've removed my sound card from my
machine, and switched back to on-board audio, but still got BlueScreens. I
tried running the Driver Verifier but I don't think I quite understand what
it supposed to do, and it didn't lead me to one particular driver as far as I
could tell.

I've run Windows Memory Diagnostic Tool several times. It did show errors,
but not every time. It seemed if one of my video or sound cards were disabled
(or removed from the machine maybe?) that I didn't get errors. I don't have
any other memory I could use to test it, and I would rather not buy more if I
can avoid it. My machine came with no drivers installed, but fully tested
hardware. So it seems odd to me that the hardware would fail days after being
tested successfully.

Anyone help or suggestions on what I could try next would be greatly
appreciated. Here is the latest BlueScreen error:
Product
Windows

Problem
Shut down unexpectedly

Date
8/20/2007 5:39 AM

Status
Not Reported

Problem signature
Problem Event Name: BlueScreen
OS Version: 6.0.6000.2.0.0.768.2
Locale ID: 1033

Files that help describe the problem (some files may no longer be available)
Mini082007-05.dmp
sysdata.xml
Version.txt

Extra information about the problem
BCCode: 109
BCP1: A3A039D8951D1542
BCP2: B3B7465EE799C424
BCP3: FFFFF80001EFFD95
BCP4: 0000000000000001
OS Version: 6_0_6000
Service Pack: 0_0
Product: 768_1