Debian has been running so well on my 6 year old Thinkpad X41 that I haven't even considered buying a new laptop. I'll probably use it as long as the hardware lasts, be it another 4 or 6 years. After upgrading to SSD and aligning the partitions correctly to erase byte size it boots up to desktop (Fluxbox) in 7 seconds and basically everything that doesn't require heavy calculation from the CPU happens instantly. In practice it's much faster in all CPU non-heavy actions than any Windows laptop I've ever used (I know SSD has most to do with this). It's also ecological to buy stuff that lasts and not replace computers every another year.
I've been repairing windows laptops lately (mostly Windows 7, some Vista) and my feeling is that almost without exception they are laggier and slower than what I'm used to. Even if these things have quadrupled amount of RAM compared to my old laptop, it really doesn't show in any meaningful way. Windows Vista and 7 seem to use atleast one gigabyte of RAM in order to just keep running as there is so much useless bloat loaded at any given time. Also many of these Windows 7 laptops seem to have audio issues on high CPU load. Even after fresh install audio will stutter when the machine is under heavy load (Ie. calculating primes).
So why would I make a jump from provenly trouble free Linux on this laptop to Windows 7? Would it not be slow to run Windows 7 on 6 year old laptop with 1.5GB of RAM? Would the SSD be as fast using windows filesystems? Would the suspend and hibernate actions work correctly and as fast as they do in Linux (suspends in one second, resumes in one)? Why would I use Windows 7 as I even don't know how to use it's user interface (how to move and resize windows without grabbing window borders with mouse?). How about most of CLI tools that make my life easier? Would I be able to use most of my favorite software on windows? (On Cygwin maybe, but why the trouble?)