This page is good too if you are planning in investing in gear:
http://bitcoinwisdom.com/litecoin/calculatorEdit: Just remember that GPU mining is another game than bitcoin asic mining, since the GPU still have some value when then can not generate a profit in respect to electricity cost, then can the cards be sold used, and if you have already reached ROI by mining, then is the sell all profit.
thanks

) this pages can help me a lot

) so if i correctly understand with this card i can mine even 1BTC in 31 days?? of course with power cost and difficulty can change

)
btw can u tell me i correctly calculate kh/s??
http://www.wheretomine.com/ type 650kh/s and take earnings for top (you should have MEMcoin as first coin)