No Memory No Video

So I decided to upgrade my Mac's memory and video card, I figure I can find a great deal at a online auction (you know who I am talking about). I bid, I win, hooray! The memory and video card arrive on the same day, which is a bonus because my Mac model can be difficult to get into. So 30 minutes later memory and video card installed, and I start my computer... Or should I say I attempt to start my computer. Nothing, Nada! After another 45 minutes of messing around I decide to remove the memory. Yes! my baby starts... but I am staring at a black screen. Darn! Video card doesn't work either.

Am I angry? Yes. Am I going to buy again? Yes. So my question is, has this happened to you?