I switched to Dvorak on my laptop about three years ago, and this is the computer I mostly use. When I bought a stationary a while later though, I kept the QWERTY layout on it. I have no problem (well, almost) switching between the two.
A while ago, I decided to change to Dvorak on my stationary as well, but I then found it difficult to type, as my fingers seem to expect QWERTY when using that keyboard. The tactile difference between the two keyboards seem to cue my brain to which layout I'm currently using, which I think is pretty cool.
So I keep using both. I wouldn't want to stop using QWERTY altogether, since most keyboards out there use it.