You should be able to make a good $329.17 per month at current difficulty and price.
However, for the $2400 price tag, your purchase is definitely not worth it. You have to account for both electric costs and the heat for AC, which will be quite significant (it will heat up an entire room pretty fast).
In the best case scenario you would break even in ~10 months, which would have been only 4-5 months if you had built a rig yourself.
In general, if you want to buy a PC, you must buy and build it yourself. Ever notice how expensive prebuilt desktops and laptops are? They are A LOT more expensive then they really are worth.
10 months is a while, but building it myself means I couldn't start for 2 months so that would mean 7 months from now vs 10. Then it also depends on what happens with Litecoins. Do they end up on MtGox? How much will that influence the rate that I break even? What will the difficulty be 2 months from now? .
Ultimately 10 months from now I'll probably have to buy a new, build or upgrade anyway or perhaps even before that.
That does not justify the $2400 price tag. It's basically the same as cutting your efficiency by 50%.
