E1705 BSOD Memory Parity Error

First off, I've searched and read several times over the past year and never found anyone who seemed to actually offer a solution to this problem other than "buy a different laptop", but I really want my E1705 to run properly without the BSOD Memory Parity Error STOP! problem like it did when I first bought it more than 2.5 years ago.

Over the past 18 months while trying to narrow this down I've replaced the ram, removed the wifi card, replaced the hard drive, put the original 60GB hard drive back in, reinstalled the o.s., flashed the main and video bios, upgraded countless drivers, downgraded drivers, removed the optical drive, removed the memory cover, used fangui to leave the fans running (which helps a LOT!), and I forget what else at this point in various combinations trying to reduce the amount of heat and eliminate possible hardware issues/conflicts, none of which fixed it.
I'm really suspecting the video ram as the culpret, and am considering downgrading the video card (yes I know I can't go all the way down to the intel video since it got an upgraded video option), but I'm also wondering about the possibility of a chipset thermal issue at this point as well.

System:

Inspiron E1705
T7400 2.16GHz Core2Duo 667FSB (4MB Cache iirc)
2GB (2x1GB) 667FSB DDR2 Corsair RAM (was 2x512MB 667FSB as shipped new, I still own it too)
nVidia GeForce 7900Go GS Video (256MB iirc)
WUXGA 1920x1200 17" Wide UltraSharp display
100GB 7200rpm Hitachi HDD (replaced the original 60GB 7200rpm Hitachi HDD the laptop came with)
CD/DVDRW Optical drive
Intel 3945 (iirc) a/b/g internal WiFi
BlueTooth internal 2.0 option
SoundBlaster deluxe HD Audio option
Windows XP Home Edition (updated to SP2 at this point iirc)
Extended Life Battery option with Upgraded Charger option
10/100 Integrated NIC
56k Internal Modem

Symptoms:

Original 7900Go GS developed display corruption due to bad video ram within the first week and failed completely within the first 3 weeks of buying the laptop while playing WoW daily and was replaced on-site under warranty which solved that problem.

A few months later Supreme Commander was max'ing out the original 2x512MB 667FSB RAM so I upgraded it to Corsair 2x1GB 667FSB which solved that personal issue.
Next I ran out of space so I ghost'ed to a brand new 100GB 7200rpm Hitachi drive, (ghost'ed the diag partition too!) which solved that personal issue.

Gaming dropped off to a rare occurrence after the first 9 months of ownership due to major new work obligations and all seemed fine for quite a while since usage was basically email, web browsing, and mild audio editing mostly at that point.

With the laptop sitting on a table with the back edge propped up an inch for better airflow playing a library of random mp3's through my stereo via the laptop's coax spdif digital audio port for a few hours (through the optional accessory video dongle cable) it suddenly began stuttering the music, then it froze for a few seconds, rebooted, and finally stopped on a BSOD about memory parity error and told me to contact the hardware vendor.  I powered it down and left it off the rest of the day and the next time I turned it back on it booted fine, passed all the diagnostics, and ran properly for maybe 90 minutes before I finished work and shut it down again.  If I left it playing mp3's for long periods it would do that again but for light use it seemed fine.

While browsing the web for a few hours one night the laptop began BSOD'ing about Memory Parity Error with the fans still totally clean and unobstructed.  After that I could sometimes browse for hours, sometimes 20-30 minutes max.  Sometimes it would work again for a while after a reboot, sometimes not.
I removed the 2x1GB memory and reinstalled the original RAM, which made no difference.
I removed the RAM cover panel for extra cooling, which also made no difference.

I installed fangui and left the fans on low full-time and this seemed to really help but if I browsed long enough the gpu temp would get pretty high and the BSOD would happen again.

With the gpu fan on high at all times the laptop seems to behave fine for many hours while browsing the web, although occasionally the bios fights with fangui and I have to step the cpu fan to high also to get the temps down enough to make the fans stop cycling between speeds every few seconds.

Using it to occasionally play a dvd movie is hit and miss whether or not it will play the entire movie without that same Memory Parity BSOD so I don't bother to use it for that anymore.
I also don't even bother trying to game with it anymore because a Memory Parity BSOD is inevitable at random if I do, which is sad for such a serious and expensive machine (>$2,200.00 when I bought it new!)...

At this point it's a glorified 2.16Ghz Core2Duo, 2GB Dual-Channel DDR2, 7900Go GS, WUXGA web browsing workstation...

ALSO, my roommate has the same machine with the exception of no HD sound option, the cheaper wifi card, the cheaper battery (iirc, same charger though!), and the original 7200rpm 60GB HDD. 
His E1705 developed BSOD problems long before mine did, his battery is bad now, his has even more BSOD problems than mine does, and within the last 9 months his video card (still his original 7900) is beginning to corrupt the display contents and cause stability problems.  He bought a huge usb cooler tray because it got so bad it wouldn't even run 30 minutes and now he can at least browse with it for an hour or two usually before the BSOD but gaming is pointless for him to even try from the laptop now.

We both bought these E1705's brand new from Dell within 2-3 weeks of each other in the late spring/early summer 2006.  I bought the 5 year NBD On-Site complete care warranty so I'm still covered but his 1 year basic warranty is long expired.

This is my 4th Dell Laptop in many years, it's the first one I bought new, and the first one I've ever had problems with. 
My last Dell was a sweet 2.4Ghz Inspiron 8200 that I bought used off Ebay from the original owner in 2003 and only stopped using last year because its' 440Go video card is totally useless for gaming anymore and it can't be upgraded any further. 

I bought this E1705 to replace that 8200 and I must say that it's been a love/hate relationship ever since.  There are so many things to love about the E1705 but this BSOD Memory Parity STOP error, which seems to be very common with this model is getting really old.  I'd sell it and buy a different model but I wouldn't want to wish this problem on anyone else.

These were still available with a Core Solo processor when I bought mine so I'm wondering if it's a thermal issue with the chassis design or maybe if the motherboard got revised at some point during the Core2Duo for all those people who have this laptop running properly?

Is there a newer motherboard revision or a video downgrade I should consider, or any other suggestions to actually solve this problem?

Thanks in advance!