What should I do?! Upgrade or not? Upgrade to what? PLEASE HELP!

Guys,

Some advice from you experts are very welcome now... I'm stuck!

I have upgraded my computer a few months ago, and now this is what I have:

ASUS P5N-D SLI 750i
E8400 Stock
8 Gb OCZ DDR2800 Gold Edition
BFG 8800GT in SLI
3x Seagate 7200.10 500 Gb in RAID 5
1x WD 1gb Green Power Series
1x Pioneer DVDRW
1x LG DVDRW
X-Fi Gammer
Multi-Card Reader
BFG 850W PSU SLI Cert.
Zalman 9500
Antec 900
Vista 64

Problem is that ever since I've built this thing I could never get something truly stable like I was looking for. Crashes, BSODs, weird lock-ups and all.

I could improve stability a lot after I:

- Bumped the memory voltage to 2.1,
- Installed the latest drives
- Flashed BIOS
- Flashed both VCard BIOS (SLI only worked after this!)
- Installed the NB fan (even against the recommendation of ASUS to use it only in Water cooled systems)
- Set up memory timings to be synced at 667Mhz
- Installed Windows One Live Care

However, I'm still not there. My Window stability index went from lousy 3.4 to 7ish, but it can't get past that... Every time is about to break the 8 barrier, something happens (software stops responding, system locks up, system does not shut down, etc) and here we go again. I've been monitoring the system over 2 months so far and I'm really upset by now.

After reading several Forums, it seems the 750i board is not reliable as it should, and many are having problems with it, regardless of the manufacturer. So, bottom line is, maybe I'll have to switch this MF to something that works.

Now, question number 1 is: Should I try to do something else?! I want to stay with Vista, so XP is not an option for me. Temps-wise it's ok (processor around 35-45 under load according to realtemp and it's a Antec 900 which has a very good airflow). Ideas are very welcome!

And, question number 2 is: If I need to change my MB, what should I get? I'm not planning to OC. I just want a good performer STABLE system! That's it. No more and no less! (I believe this is not asking for too much).

Your comments will be very much appreciated!

Thanks in advance for the assistance and sorry for my english language mistakes!