You want 559 USD so let's call it an even 100 BTC at today's prices.
Your rig should do about 750 MHashes/sec according to your post here: https://bitcointalksearch.org/topic/m.718502
According to my calculations this will yeild about 0.5 BTC/day (maybe a bit more) at the current difficulty
So it looks like your payback period for just the principal, in terms of BTC, is about 200 days.
On top of this you have to pay for electricity/cooling and interest back to your lender (me) for the loan.
Does not look too good to me. If your calculations are different from those above please let me know.
EDIT: Ok I see from the on line calculator you used you could get as much as 0.60 BTC per day so that gives a principal payback period of only 167 days - much better. So it really boils down to your actual BTC production rate over the next 6-9 months which in turn boils down to the estimated difficulty during the next 6-9 months - a very difficult number to estimate.
Your 2nd calculations according to the calculation on my previous thread seems to be about right. Also, do note , that I am not going to be paying you back with the profits incurred. I will be using half of the profits + my own money to pay you back. So worst case scenario, you will get back your money + interest in 6 months time. Best case scenario, and we make some profit you'll get your money quicker + the interest.
The reason why i want to partake such methods is that I am interested in bringing up the community over at my country, Malaysia. Since I am now doing my Degree in Security, perhaps I could intergrate my assignments with the concept of bitcoin as well. Maybe start a club / organization and show people what it takes to do this. Then maybe we'll get more people mining and thus building a community over here.
Of course with the profits, we could help some students with loans as well to get started. Maybe get a professor involved if he / she is interested in this concept. The possibilities are endless but to achieve all that we would need somewhere to start and this is it. Of course i understand that the loaner would have to think twice about getting his principal in 6 months time , however he will be paid monthly based on the profits made. Regardless, he will be paid. There will not be any deferment of payment.