I'm looking for a half-height PCI multiport serial adapter that will work with both Windows 2000 and Red Hat Linux 7.2. Do you have any recommendations?

Two products that immediately come to mind are Digi International's Digi Neo, which supports four or eight serial ports, and Comtrol's RocketPort series of adapters. The Digi Neo is the smallest PCI multiport serial adapter I've seen. Installation in Win2K systems is a breeze; installation in Linux is more difficult but does work. Most of the RocketPort adapters are less than 5" long, but I don't believe that any of them are half-height.

You might also consider a network-attached or USB solution. Both Digi and Comtrol make network-based serial adapters that offer Win2K and Linux support. These adapters typically have drivers that load on the client and provide the appearance of locally attached ports. Digi's Edgeport and Hubport USB-to-serial converters work well with Win2K, and although installation on a Linux system isn't a simple Plug and Play (PnP) process, the converters will work with Linux. These converters are great for adding multiple serial adapters to notebooks.