First build, dual boot, big mistake?

[SDD]

Please tell me if I'm walking into a lot of trouble with my plan:
I'd like to build a dual boot system, to be in an entertainment room where it will share space with audio and television components, for home theatre and also for Web surfing on a big(ger) screen.
One OS will be Windows XP or Windows Media Center, the other OS will be Linux (I like Ubuntu).
The Windows side is so my wife can/will use it. The Linux side is because I like the challenge of trying to get a Linux HT working (e.g. MythTV) and because it isn't Windows (sorry fans).

Now, the question:
To make booting the OS *really* simple, I am thinking of using those slide in hard drives, I think they're called mobile racks. Slide in the HDD tray with the desired OS, power up, viola! Changing the OS is as simple as changing the HDD tray. But am I creating additional issues for myself with this configuration? I can't think of any additional problems that a mobile rack should create for me, but then, how would I know? I haven't buit a system before. Your advice will be appreciated.

By the way, reason for thinking mobile rack is two-fold: (1) anything more complicated than turning on power to get boot up will be resisted (that is, no boot menu, please; e.g., absolutely *no* wifely interest in looking at my dual boot Apple with Bootcamp into Windows); and (2) I find that switching between MacOS and Windows is not totally transparent on my MBP with respect to some peripherals and settings, so I figure keeping the OSs separate on their own dedicted drives might keep things nicer.

Thanks,
SDD

[glc]

That's a good way to do it.

[SDD]

glc, thanks for that feedback.
I'm finding that selecting components will be a bit of a challenge.
For example, DVI out on a card that works well with Linux is not easy.
Since I want internal DVD/CD drive, and the mobile rack, I'll probably have to go with a 3U server case, since I've not seen HTPC cases with two front 5.25 bays.
etc.

[glc]

What about a standard ATX desktop case? Most of those have 2 bays.