There's only one way to find out if it is bootable and that's to stick it in the drive and reboot. Most distros come in bootable cd form these days.
Look
here for installation instructions.
'IPCop takes over an entire hard drive' it says. so if you are worried about writing over your current one then remove it from the machine before you boot up.
You should have no problems with the 1.6G drive, as long as it's on a standard interface, SCSI or IDE etc.
The site linked above also conatins links to the latest .iso images, and they 'are' bootable.