I am also a big fan of the Topeak Explorer Rack and MTX DXP Trunk Bag combination. The rattle bothers some people, but not me. I find that if the volume on my handlebar-mounted mp3 speaker is set just right, NONE of the sounds my bike makes bother me!

Seriously, though, there are several easy tweaks to stop the rattle, which is common on this rack, but the good news is that they are not mandatory because the rattle doesn't affect the security of the system. The bag fits securely on the rack without undependable bungees that can snap off and get tangled in your spokes, Best of all, it slides on and off nice and smoothly so you can commute like a gentleman, or a lady.

There are many good rack and bag systems out there that will be just fine if you don't mind spending the extra time securing the bags every time you get on. So unless you are going to buy one of the Topeak bags with the Easy-Glide hardware (my recommendation), you probably don't need to invest in a Topeak rack.