You have forgotten a quadruple boot (add Windows 98SE)!! I can quite unerstand keeping XP and W7 for a while, but after checking that everything works in the new system, why keep it active? I am about to change to W7 from XP and am debating 3 options:a to make a clone of my C: drive to a spare external drive so I could revert in a doomsday scenario,b: a dual boot as you suggest with XP and W7, or c: with W7 Ultimate to invoke the XP emulation and virtual disc it offers.In any event if, hopefully, w7 works ok I will move on and abandon the old system, which I was loathe to do with Vista, which I never bought.
Just to fibish off this thread - I booted from the W7 32bit disk and did a custom install into my newly created partition. I then used EasyBCD 2.0 beta to tidy up the boot screen ("Previous version of windows" and the default) and touch wood it all seems to be working OK.
I am going to use MS Security Essentials (anti virus) when I switch to W7, having read a number of comments re AVG on these forums. Some say MAB still works. I think CCleaner is ok, and I have always used the normal MS Defragmenter.I also believe the built in W7 Firewall seems fine.