Well I know this will probably start a debate that's happened many times in these forums, but I'm in need of some specific input...

Through some patient searching, I've purchased a 2007 Trek XO1 for an unbeatable price. I want something that I can use for fitness, some commuting (most of my commuting is on my 1972 Raleigh Sports 3-speed), long weekend rides, etc. I've always been partial to steel bikes but I'm tempted to keep the Trek, especially given that it's my exact size and weighs about half of any bike I have now (alloy wheels make a huge difference, huh?). I bought it because the price was too good to pass.

For the criteria above, is it worth keeping the Trek, or should I sell it and put the profits (couple hundred dollars, probably) into something else? Would a nice used steel give me more durability than the aluminum Trek? I see lots of comments about CX bikes being good commuters, but does that also extend to my other needs for a bike?

Thanks for looking.