Manual & Raw v raised ISO

I have always just raised my ISO whenever the need occurs on my 30D's

Now i'm thinking, as I shoot in raw always, can I do it another way by using manual.

Say I shoot raw and in manual on a shutter speed of 1/60 (assuming this is the min to avoid blur) and use ISO 800. To perfectly expose the pic maybe I should have had ISO 3200, but go home and change up the two stops in raw (or maybe use exposure compensation in camera).

Will this have any difference to the noise, other than if I had just shot in 3200.

I am going to a show where I need to do this quickly, so don't really have time to experiment.

One part of me tells me it's the same end result, but i'm not sure

I think you will get more noise at iso 800 underexposed by two stops than a bang on exposure with iso 3200

You will get more noise by shooting underexposed at iso 800 and then bumping it up two stops in RAW. Also, you will lose a lot (most) of your shadow detail in the final image by doing this, as you are effectively cutting off two stops of dynamic range.