No, sorry if that wasn't clear. The 9800GTX+ and all other PCI-e graphic cards would fit into the 16x PCI-e slot (none actually use two slots). However, the 9800GTX+ requires two PCI-e power connectors
, which come from your power supply in order to power up the graphic card, not two slots. I suggest you get a GTS 250 instead which uses less power and only needs one six pin PCI-e power connector, and provides the same performance.
That is what a six pin PCI-e connector looks like.
I hope that this makes it clearer.