Sometimes huge improvement in noise can be accomplished by being even more precise in your exposures, also the more I work with a combination of the original exposures and my PP, I become amazed now much better my camera seems now at higher ISO's and I thought I was doing really well before.
I've a friend who does a lot of wildlife/scenic/landscapes with a 30D and the work is simply stunning, and there are times I'm amazed at the quality and beautiful images I've gotten out of my little Canon G9 point and shoot as long as you're not pixel peeping at 100%, just doing things like the internet and making really nice prints, not murals but you can sure get good photos out of these cameras. What you have is a really good camera right now today, it's so easy to move up only to have the manufacturers fill a need by upping what the new cameras will do, that need of course works with their profiting too which is also fair but having been there, life is so much sweeter when you have no debt; I am very grateful that every bit of camera gear I have is paid for.