The illusion is real.
Fortunately, theere are facts available to prove it:
This 17" Asus, for example, is even cheaper than the 15" macbook:
http
/www.newegg.com/Product/Product.aspx?Item=N82E16834220704
Even though it costs much less, it is still faster than the 17" macbook.
Please note that I am only talking performance per dollar here. You gotta remember that PCs and Macs use the same hardware (except for EFI vs Bios) and apple is considered a premium brand (some will disagree). Being a premium brand, thy will not aim at maximum performance, but on design, quality etc.