Nah im not an xbox fanboy as you put it lol infact i have all 3 consoles with the best titles on each platform.including Uncharted 1&2 Resistence 1&2, Killzone 2, and even the consoles best game MGS4.
If it were just 'colour differences' between MW2 then that would be ok but its not just colour differences..the whole image looks terribly washed out theres less detail and lighting is not up to par either.. heres a couple examples with the ps3 version being on the left and xbox on the right.


Aside from the look, the xbox version has a better framerate and finally but most importantly it comes down to the multiplayer aspect of the game..only a ps3 'fanboy' would say that PSN is as good as xbox live whereas it honestly doesnt even come close..yes its free but it truely shows that a free service doesnt mean a good service.
2million people were on mw2 online simultaneously and that didnt cripple or slow xbox live down at all, whereas the ps3 had major issues online upon release with alot of people not being able to play the multiplayer.
As for competitive gaming just go onto gamebattles.com to get a cross section of the number of people choosing the xbox version over the ps3... you will see how many EU teams there are for the game for each of the consoles.. over 6000 for the xbox 360 and just 1200 for the ps3. The xbox version sold double the amount than the ps3 according to one report http://ps3.qj.net/Xbox-360-Call-of-Duty-Modern-Warfare-2-sells-more-than-PS3-so-far/pg/49/aid/135902
Im not a 'fanboy' i just know what im on about.