I wrote earlier this year about buying an i5 based Toshiba laptop. I have been struggling a bit getting things just right using Linux, but I am there now. Installing the final non-beta version of Ubuntu 10.4 and working a little to automate wireless connections made the difference.
I still love my MacBook with OS X and use it for casual use but an i5 laptop with 4 gigs of RAM and a half a terrabyte of disk for 40% of a comparable MacBook Pro is a story that is difficult to ignore. I admit to being frugal, and lightening fast inexpensive hardware running Ubuntu makes me think that Apple should drop their prices (easy for me to say: I sold my Apple stock when I made about 4x my investment).
I have Windows 7 installed also on my i5 laptop and I am happy to have Windows on some rare occasions but dealing with very long boot up times, the overhead of anti-virus software, a poor command shell even with bash installed, and the difficulty of using a lot of development software dooms Windows 7 to a nice to have toy, but I might someday trash it to get back my 250 gigs Windows partition.