I'm looking at installing red hat 7.3 on a laptop at work so that we can test out some of the linux software that we are selling.

To avoid having anything go wrong with the laptop (which is a Dell Precision M60) I'm thinking about buying an external HD and doing the install on that...

Is it likely that I will be able to boot from an external HD (probably USB 2.0) using a bootloader (i am a relative newbie to linux..) and keep XP as the default (ie. could I boot to linux if the HD was connected AND boot to XP with no problems when disconnected - other people have to use the laptop as well)

I know that it is probably simpler to partition the internal hard drive and use that but even a small chance of the computer being out of action for a day is pretty much unacceptable.

Any ideas?