With $1700+ to spend, really struggling with mac vs everyone else syndrome!

if someone can help here.
My wife and i are taking a trip overseas and we need to get a new notebook before we go.

I love my iphones, ipod touch and imac and love mac but i have the struggle with specs that im sure others have had.

every time i go to apple's website and see something with a core2 duo vs these new sony and asus machines with new i7 (quad core) cpu's i start to rethink it all!

can someone tell me whether or not i am making a mountain out of a molehill? specifically the i7 i am looking at are these intel i7 729qm clocked at 1.6ghz but it seems that these processors have less of a clockspeed race than a features race...

i dont even know if that cpu has the visualization features built in. Intel has some crazy marketing and product lines.

specifically i am looking for as much speed as i can get without sacrificing much.
i also understand that in 2-4 years (the amount of time which i expect to use the computer for) that os x will likely seem faster than windows 7 will... i fix computers and have seen old "lamp style" imacs that seem faster than 2 year old pc's and i think that the OS has a lot to do with it.

I guess also that os x is written around the CPU and the i7 will have to run whatever, but windows will never be written just for that cpu. that may play a part in it.

but that aside i also want to put windows 7 or xp on it and play games with it attached to my HDTV.... and i also need it to work as a media center so i can get HD tv shows and output them to the same tv... the files are in MKV format usually and so ill be outputting them to that tv via dvi or HDMI (depending on the computer as apple doesnt have HDMI) and using VLC to play them.

so whats the path here?
thanks for any sort of help...