Onboard graphics runs with dedicated card?

Hi I have an old system (dell e310), it came with integrated intel graphics controller but its terrible so I decided to put an ati radeon 9250 pci in my pc because I wanted to play some very very old games, it works just fine for me even though its such an outdated card. I uninstalled integrated video and disabled it in the bios to use the new card but for some reason everytime I boot, windows starts installing the old integrated video. Why? is this ok?
also, when I had integrated video I could play youtube videos in HD (even though my cpu was at 95%) now If I play a video in full screen (any quality) it freezes all the time and my cpu according to task manager is only at 20% also sometimes it takes 3-4 seconds to minimize a windows (its like in slow motion)

system:
2gb ddr2
160gb hdd
windows xp/7
500w psu

I tried reinstalling drivers and putting the card in another pci slot, no luck. monitor is plugged into the new card.