...Or you could answer the darn question. I want a new computer that can at least run Arma 2 OA at medium settings pre-built, what kind of computer should i be looking for?
The way you wrote the OP sounded like you were getting a new PC just because your old one had a virus, which as Medivh said is like shooting a mosquito with an ICBM (ie it's an overreaction). Sorry for trying to be helpful.
Anyway, Arma II is three years old now, so any relatively high-grade hardware released within the last four years should run it very well. Shop around on sites like Newegg, it's not that hard.