I suggest you to go for RX470 or RX 480. Sapphire or XFX. Get a solid processor and please don't go for windows 32 bit. All miners are designed to run on 64bit.
Not 100% true - but generally so.
There *is* at least one 32-bit miner out there, for NVidia mining XMR.
Counting on a 32 bit OS to mine on however is a VERY BAD idea at best.
The 7990 should be a solidly profitable card if the OP has a low cost of electric, running ZEC or ETH, and might very well cost LESS than a RX 480 or RX 470 at current pricing for the things for a TON more hashrate abet at a lot higher power draw.