Not to criticize your work too harshly, but you specifically call out that this showcases attention to detail, and it's actually very inaccurate to the actual Windows XP, for anyone who's ever used it before. The UI elements are all haphazardly sized relative to each other, there are alpha-fade ins/outs, the loading bar in the boot screen animates smoothly when the real thing popped along block-by-block, fonts are antialiased when they shouldn't be, hover-over dropdown menus appear/disappear instantly when moused over, the fake scanlines are just a pixel grid overlay, the selection box on the desktop is filled but should be a dotted outline... these are just the few I saw and I haven't used XP in years.

no offensive taken dude, great eye you have and at some point i'll go through and see if I can address each of these things

aside from the pixel grid effect - thats just there for fun and I like it

I agree with you, but also I feel that that's way too much work for a portfolio site, and this is good enough for me.