Angels & Demons doesn't "feel" like HD

[bogdan]

Hello guys, I'm new to this massive forum and source of the best information in Blu-Ray.
I'll try to be as explicit as possible with the problem I am concerned about. I will inform you about every minor detail I think it's related to my Blu-Ray experience.
Here we go: I have an HDTV, the 32 inches LG SL8000 (very fine and crisp detailed when playing, let's say, 1080p trailers from Apple Store, so the TV is working very well). I have it connected via HDMI - DVI cable to my PC, to a 9600GT video card to be more specific.
Less than a week ago I bought my first Blu-ray movie (Angels & Demons 2 Disc Theatrical & Extended Edition - not that, but the same with more subtitles, for my country too). Alongside it, I bought an LG BD optical drive, so I can start my own BD disks collection and to have the hardware to play them on.
For a player, I use Arcsoft Total Media Theatre 3 software.
Ok, so I inserted my A&D disc movie in the BD drive, launched Arcsoft and started to play the movie while selecting the Theatrical Edition stream. From the 3 trailers in the beginning ( T: Salavation, Taking of Pelham 123 and 2012) to others scenes in the movie where I skipped to test my new hardware, I noticed too much grain and inferior quality to what I knew Full HD 1080p BD Disks represent. I compared it with the screenshots here on the site and, yes, it kinda looks the same, maybe better on my TV (however, I read the disclaimer at the bottom of each screenshot that it does not reflect the true quality of the image). I think it's blurry too. In the review, the Picture Quality scored 4.5 BD stars so I don't know what to think. Am I doing something wrong or it's just the movie? Downsampling maybe?
As I said in the beggining, I want to get you all informed about minor details in my computer hardware and software that may have a chance (very little to zero I might add) to be responsible for the BD to perform as I expected (again, it's my first time I see this movie on BD and I don't know how it should look, I just think it should look better..).
First of all, I'm using Win XP SP3 so I have the AHCI mode that enables SATA disabled in BIOS. However, all my HDD and optical drives connections are made through SATA connections, but because disabling AHCI, they appear in BIOS like being IDE drives (my LG BD is seen as Slave). On other forums, users just told me it's nothing to worry about that, but who knows...
Second and last thing that went through my head is that I had to update my UDF drivers with Toshiba ones to 2.5 version, because my BD Disk was not showing off in windows explorer (known issue for Windows XP). Now I can see the disk, it has a massive 46,4GB

I am sorry for this wall of text, but in the last two months I spent a lot of money that I have saved with some sacrifices to have an entry-level home theater, so please try to make clear what's going on.
Thanks, Bogdan