One is WinXP/SuSE 8.2 and two are WinXp/Fedora. I'll probably change at least the SuSE distro to Debian soon.
I'm not presently running any of these with partitioned single disks, although I have in the past. I'm a bit of a space hog on my most frequently used machines, so I've found that the best solution is to simply buy an additional hard drive for linux. My typical setup is 2 80 Mb drives with WinXP and the bootloader on the primary drive and linux on the secondary.
It works great for me with one caveat-- file sharing between the WinXP and linux sides of a single machine. With NTFS file systems on the XP drive this is awkard-- there is a kernel module that lets me mount and read NTFS files systems from the linux side but not write to them. I use VFAT filesystems on one of my XP disks to get around this problem-- linux can both read and write on VFAT partitions, however XP cannot see the linux file system at all, period. Typical MicroSoft head-in-the-sand.
The cable modem setup is easy during installation.
Don't use an older RedHat branded distro-- get the latest Fedora 2 disks (downloadable) if you want to go the RH route:
http://fedora.redhat.com/I use the XP side for a relative few apps that either have not been ported to linux or for which equivalent linux apps don't exist, or for special situations-- for example, the lecture halls where I work ONLY support Powerpoint, so I use XP PowerPoint to assemble my lecture presentations.
You might also check into running Crossover Office on a single boot linux machine if you only want to run the windows apps it supports, e.g. MS Office and Photoshop.