I'd start with just leaving the word out. "This piece of software is useless." will most likely convey your point. Perhaps, if you wished to ramp up the emphasi

I'd start with just leaving the word out. "This piece of software is useless." will most likely convey your point. Perhaps, if you wished to ramp up the emphasis, you could say that "this piece of software is totally useless." I also like the word "profoundly" for extra emphasis.