Cyclocross - "Building" a CX bike?

I've got a nice road bike, but it isn't very comfortable and seems kinda "flimsy" under my clydesdale butt. Pondering going to a CX setup, but...

Can I just buy a CX frame and fork, and switch over most of my roadie components? Will Shimano 105 brifters operate SRAM disc brakes? Or, is there a way to modify the 105 brifters to make them play nice with discs of some kind?

Will the rest of the components (105 also) work on a 'cross bike, or would I be better served to just sell the roadie and buy a complete 'cross rig?

Most of the components should transfer over. Some possible exceptions:

You may run into issues with the front derailleur clamp size, depending on the differences in frame tubing size.
105 STI will pull road specific disc brakes just fine. Make sure you get road specific mechanical discs, like the Avid (SRAM?) BB7. Careful, there's a mountain version of the BB7 as well.
Also, your disc brakes will require disc wheels.

Most of the components should transfer over. Some possible exceptions:

You may run into issues with the front derailleur clamp size, depending on the differences in frame tubing size.
105 STI will pull road specific disc brakes just fine. Make sure you get road specific mechanical discs, like the Avid (SRAM?) BB7. Careful, there's a mountain version of the BB7 as well.
Also, your disc brakes will require disc wheels.

i wasn't aware that there were different versions of the BB-7's... but i did know i'd have to change out wheels. actually, the wheels are my biggest complaint about my road rig. so i was pondering "downgrading" them to something heavier, and heavier duty, anyhow...

or would I be better served to just sell the roadie and buy a complete 'cross rig?

I'm thinking yes, buy a cross bike.

http://www.bikesdirect.com/products/motobecane/fantom_cross_cx.htm

http://www.bikesdirect.com/products/motobecane/fantom_cross.htm

http://www.bikesdirect.com/products/motobecane/fantom_cross_pro.htm

Tim