KVM SWITCH DIY

Is there such a thing as an external email notifier (e.g. a USB light)?
I’ve found a DIY USB kit and a discontinued product that connects to a PS-2 port. I have two computers hooked up to one screen (via a KVM switch). One computer is acting as a cash register and runs a propriatory OS. The second runs Windows XP and occasionally receives orders via email. I need a visual way to know when an email has arrived. Something such as a flashing light would be great.
I don’t know about making a light flash on a usb device, but I use Eudora e-mail (it’s free, http://www.eudora.com/) and there is an option in its settings to play a sound (it accepts many media file types) when it receives an incoming e-mail. If you try it, the setting is under Tools > Options > Getting Attention.
Or, if you don’t want sound, maybe if you have a USB Flash drive with a light, you could put the sound file on that Flash Drive, and when it plays the sound, maybe it will make the light blink (since it is accessing it?). This would work even better if you had a floppy drive. Point to a sound file on a floppy disk, then keep the disk out. When it tries to access it, the floppy drive light will blink and it will make that noise it makes when there isn’t a floppy in there
Just getting creative
Zonet KVM Switch Review & DIY Fix 7/19/09