Have FS 2004 installed on my laptop and desktop. Having the same problem on both...none of my aircraft will fly level. The nose is always .9 degrees up. The only way I can counter this effect, is to apply flaps during cruise. 

Contacted Microsoft about issue and they did not know what is causing this. The tech told me he installed the program and he was not experiencing this issue. I dont know what to believe from them.

Help and/or ideas will be greatly appreciated!!!! Thanks!

-Jonathan   

planes rarely fly level with the nose locked on the horizon

you need to give it some pitch (angle of attack) in order to get it flying straight
.9 degrees is perfectly normal for cruise speed, this is not an issue, it happens with every plane

you can also use the pitch trim to help adjust your attitude

I'm wondering if he means 0.9 degrees or actually 9 degrees, he seems pretty serious about it.  

But to relief Jonathan. During cruise your nose can pitch up from everything from 2 to 5 degrees. This has to do with some advance aerodynamics (which I will leave out), but as you continue the flight, the pitch will decrease slowly as you get lighter.

Edit: What Crag said.

ahh...I think the reason might be the stabilizer trim.
If you have not trimmed it properly, you have to constantly apply control column force to maintain desired flight path.

assign joystick button to 'elevator trim up' and 'elevator trim down'. This in turn will make you able to control the angle of the horizontal stabilizer, which is very important in real life

check your cruise speed and altitude

your regular 747 will fly at about 30,000 feet at 330kias

also, have a look in the FUEL AND PAYLOAD screen to see if your center of gravity is not way off (happened to me once, all my planes would tend to the left, and it took me a while to figure it out )
or maybe you just got too much weight on it

Yeah mach numbers are the deal.
Cruise speed for the 747-400 is typically m.85, but you'll be flying higher than 30.000ft though (we want to be fuel efficient here don't we )

ok. i thought i had a problem with this a long time ago too, so ill try to explain this simply. straight and level flight does not imply that your nose is level with the horizon. it says that your vertical speed is zero. physiscs 101: planes MUST pitch up to maintain altitude (conventional planes at least). look, as long as youre not losing or gaining altitude, you are in level flight. and the higher the cruising alt, the more pitch up you get. i am an avid fan of the LA-Sydney route, and i am a seasoned veteran having flown it more than 40 times. my nose ALWAYS pitches at least 5 degrees up until the very last leg of the flight. so, once and for all-so long as your VS is zero, you are in level flight. i too used to add flaps at cruising alt to level my plane out! (in the B747, 1 degree of flaps is deployed automatically at cruising alt for stable flight-but, of course, u have to do this yourself) so, i hope that helps. please tell me if it did! and also, if you land ILS, tell me if u have ever had problems landing at Sydney with the glideslope, cos on two of the runways it doesnt work for me.

actually, i heard it in a cheap movie somewhere, i put it in just to see if anyone would pick up on it  (seriously, i did!)