I've been using Avast Home for over a year, alongside Comodo 2.4. Recently auto-updated to Avast 4.8, no problems, and 3 days ago installed the latest Comodo 3.0, with D+ (training mode, mainly). Not a single problem, and the latest CFP 3 seems a lot more streamlined than the first version 3 I tried.
XP, SP3. (no problems there, either.)
I'd say it's a smooth and fairly low resource combo.