That might be because Windows 7 NEEDED more progress than Snow Leopard needed since 10.5, especially coming from Vista, ever thought of that?

Leopard was an excellent OS, Snow Leopard just improved on it and lowered the footprint by removing old PPC code. Vista was NOT an excellent OS.
From time to time I see many people saying this without an explanation. I run Windows 7 (every now and then just for kicks) and I see nothing special over Vista honestly. Big WOW that you can snap two windows side by side, it's not a big deal. I recognize that W7 handles memory better than Vista but other than that, I can't give you a long list of greatness about it and neither can most people, they just what you say, "Windows 7 is a great OS".
Now in terms of Mac OS X SL being a great OS, at least I can say what makes it great. Stacks, Expose, Spaces, Quicklook and Time Machine, Exchange Server 2007 support (without the need for MS Office) coupled with a very small footprint on my hard disc greatly improves my day to day productivity and that makes it a great OS.
Now, if the OP cares less about the OS then just get the Alienware but watch out for the low contrast washed out screens, they are notorious for putting them in their notebooks unless you get their top gaming machines. All the current Apple notebooks have high contrast screens with large vertical viewing angles.