Does anyone anticipate any significant difficulties flying with a new in box desktop PC in my carry-on rollerboard from a TSA perspective?
I would also like to know if a metal stand for an LCD projector would give me any problems. Checking the stand is negotiable, checking the computer on US Airways is absolutely out of the question.
The last time I flew with a desktop computer as a carry-on was pre 9-11
The computer will not be any problem, in my experience. In general, electronic items are fine, although they may (but probably won't) hand inspect it.
I'm not sure what you mean by a metal stand for an LCD projector - you mean one of those portable folding tables? Probably also no problem, although that's less predictable, especially if the legs come off completely and look like a weapon. (I often travel with a big tripod, which no one has ever complained about).