Since installing Vista Home Premium (32 bit) my Dimension 9150 regularly freezes completely requiring me to press the power button.  I have spent hours searching the net for a solution to this problem without success but I have established that many others are experiencing similar problems and not only with Dell machines.  Like most others I had no such problems with my previous installation of Windows XP.  In my attempts to fix the issue I have tried the following -

1. Reformatted my drives and installed Vista on a single drive in non RAID arrangement (I have 2 SATA 250GB Western Digital drives) and updated Windows before installing the latest chipset and hardware drivers.
2. Reformatted my drives and installed Vista on a stripe 0 RAID array and updated Windows before installing the latest chipset, Matrix Storage Manager (latest v7.8 from Intel) and hardware drivers.
3. Removed all non essential cards/components one by one including memory sticks.
4. Disabled all but the essential items using MSConfig.
5. Removed the iaStor Parameters listings within the registry.
6. Connected my drives to the unused SATA ports.
7. Updated the firmware of my Philips DVD8801 DVD drive.
8. Connected my DVD drive to the remaining IDE port by swopping the plug on the interface cable.
9. Installed the latest Intel chipset drivers for the Intel 945GV Chipset family.
10. Ran thorough Dell diagnostics, Microsoft memory diagnostics, Scisoft Sandra diagnostics, Mad Onion 3D Mark all without any reports of hardware faults.
11. Checked my power demands against my power supply.
12. Removed and reseated all cards and memory even my processor (and yes I correctly refitted it with adequate heat sink compound).
13. Switched off the indexer by entering Services and disabling.
14. Disabled Windows Defender.
15. Disabled Windows Firewall.
16. Disabled all Windows Power Saving services.
17. Torn my hair out in frustration.

And still the problem exists.  I am currently running the system with a fresh installation of Vista on a RAID array (stripe 0) and in all other respects the machine operates perfectly and fast.  Then it freezes for no apparent reason.  This can ocurr at any time and I have been unable to determine a pattern.  Vista does not log a problem so no help there.  The freeze ocurrs at various time intervals sometimes after hours of use other times after only seconds.  Sometimes when simply moving the mouse on an empty desktop and other times when using media centre, games or any other software I choose to use.  The act of dragging a window can cause the freeze.  It can happen when watching TV or DVD within Media Centre.  Browsing the net.  Typing an email etc.  You get the idea.

The only thing I have noticed is that after I press the power button and restart the machine there is a lot of hard drive activity after Windows starts.  I have not yet figured out what this is but it does not appear to be the indexer.

So does anyone have any ideas what is going on.  I am about to revert back to XP but would prefer not to as I like Vista in general and in particular because I spent money buying it.

List of hardware follows -

1. Pentium D 3.20GHz
2. 2046 MB memory
3. 2 Western Digital 250GB drives
4. Philips DVD8801 DVD drive
5. MSI Nvidia Geforce 8800GT
6. Soundblaster Xfi Music
7. Pinnacle PCTV DVB-T Dual TV Card
8. Belkin Wireless G USB Network Adapter
9. Logitech S510 wireless keyboard and mouse (USB)

I would be grateful for suggestions.