Installing Windows Vista Ultimate 64-bit on DELL XPS M1330

Well, I am not doing something new here. I bought DELL XPS M1330 last year. It came with following configuration:
Intel Core 2 Duo T7500 (2.2GHz)
3GB RAM, 160GB HDD (7200rpm)
nVidia 8400M GS 128MB Graphics Card,
Intel 4965 Wireless card
9Cell battery
Pre-Installed Windows Vista Home Premium 32-bit.

Well, I did buy Windows Vista Ultimate (32 and 64-bit), so upgraded the machine without any problems though, to Vista Ultimate 32bit. It worked pretty well, and smoothly. Surprisingly Windows Vista does search all the updated drivers automatically, if the machine is connected to internet and install the most appropriate one automatically.

So long story short, I always wanted to have or to feel 64-bit taste. And one crazy day, I made a decision and started the installation. As soon as I completed the first stage of 64-bit installation of Vista Ultimate, I didn't get any success as I was getting BSOD (blue screen). I was unable to look into the error too because machine restarts within seconds as soon as it displays the error. So I spoke to DELL technical support and spent more than 24 hours (in three days) and issue was ATA/AHCI settings in BIOS. Frankly speaking, I really dont know what is the difference, but expert suggest that it should be AHCI.
I followed the instructions given in the following post, and believe me, it is very good and informative, though you will get lot of new information too, here you go:
http://forum.notebookreview.com/showthread.php?t=158277

Also, I refer following websites while investigating on the issues:
http://support.intel.com/support/chipsets/imsm/sb/cs-020644.htm - This website will explain about the chipset installed on your machine and also gives you insight what needs to installed, version etc.

I followed the steps given in the following post:
http://forum.notebookreview.com/showthread.php?t=164159. Before that I installed Vista Ultimate 64-bit in ATA mode (Flash Cache Mode was OFF). And then followed the instructions given in this post. Did the change in the BIOS (as given) and it worked without any problems. And then I followed the instructions as per the first post (http://forum.notebookreview.com/showthread.php?t=158277).

I was very frustrated earlier while talking to Dell technical support, but patiently executing all the troubleshooting steps as they were telling.

Now this laptop is working fine, and windows update is going on right now, while writing down this post using another computer :).

Now the next step is to upgrade the RAM from 3 GB to 4 GB to fully utilize the 64-bit environment.