Hi everyone,

I have an urge to get my hands a bit dirty. I've been startign to commute on my roadie and it's making me a little uncomfortable. Basically I can't be as mean to it as I would like and I have to clean it so often (it's white). And even the smallest amount of water on the ground makes me keep it inside.

So I am thinking of getting a dedicated commuter bike to ease my mind. The trouble is I'm trying to do it on the cheap side, so I am considering options that make a good commuter whilst also being cheap.

There appears to be more and more new bikes available especially targeted as commuters. But for me they are a bit pricey, especially disc brake versions (which is what I would like). So I am thinking of commutafying a decent second hand mountain bike if I can get my hands on one.
There are a number of options to make it more commuter friendly, these include of course...

-Changing knobby tires to slicks - as thin as the rim will allow (I think it's normally around 1.5")
-Changing suspension fork to rigid fork
-Swapping wheels to 700c to fit an even thinner tire on (probably 700 x 28)

So my questions relate to how hard are these things to do, both in physically doing them and figuring out compatibility issues. For example, changing a tire is relatiavely easy, but how can you find out the thinnest tire able to fit on your rim?

Regarding the forks - how do you figure out what a compatible fork is? I would probably get this one installed by a pro.

Swapping wheels - again, is it possible to go to 700c on all MTB frames? Particulalry if you want the disc brakes to stay.

And I'm not feeling in the mood to give up and just by a cyclocross.