A new ASUS SATA DVD drive is like $17, so skip the converter there and just get a new DVD drive.
Hard drives are going up in price now because the factories are flooded in Thailand so if a new HDD cannot be in your budget, you can get a convertor like this. http://www.newegg.com/Product/Product.aspx?Item=N82E16812206002
You will need one for each drive you want to hook up.
SATA cables are most usually included with your new motherboard.
What Nvidia cards did you list? So far the post you have made have been kind of confusing. It would help us out a lot if you filled out the link in my signature.