the trouble is your monitors too big!

you should downsize it to 19" and then you will probably find that you can then rotate it.

I have a 27" monitor and I'm starting to get annoyed by most classics. I have to add a bezel to robotron because its not really playable at that size. You need the perifial (sp?) vision thing going to get into the zen of robotron to see the guys across the screen without loosing focus on your guy. The larger screen is really only good for fighters... but even then... I have no troubles at all playing on my 19" + dreamcast with SFA3 games. They look great. You only notice the difference when you notice the 27" mame machine sitting next to it.

I would trade my 27" for a rotating 19" in a second... But I like the classics that only came in 19" anyway...

but... (and a big one)

I hear that adding rotation to a monitor will take more time then building everything else.