When you search the part number at bing it will get you to where you see the tigerdirect discount price. Click that and it pops up a window to enter your email and the scramble word. After that it will put you at tiger on the products page, but there won't be any visible sign of cashback. Don't worry, just add to cart, checkout and login, enter coupon code, finish payment. The bing transaction should come through in at most a few hours. If it doesn't... All you have to do is email them with a cppy of the invoice and they'll pay it.
this is how transactions work for sites who normally wouldn't have cashback integrated into checkout. They keep track with cookies... So don't close the window or do anything but buy it after you click the link at bing. If you think you messed up. Close everthing and run a ccleaner then start over fresh.