video/ BIOS settings for M55p when adding video card?

[momstoy2]

I have acquired a ThinkCentre M55p (2007-D1U) off Craigslist. I now have it at 3GB RAM, a new DVD burner because the original combo drive croaked, and found a used (also Craigslist) GeForce 8600GT 256MB video card to try my hand at. I am running Windows XP pro from the original 80GB hard drive. The video card is used so I spent $30 gambling that it will work, but what the heck-I cannot afford a new desktop right now and this fit my budget.
I bought this particular video card because it has been mentioned in the forum and I found what I thought was a good deal on it locally. After looking at the BIOS settings for the integrated video I thought I would ask if another forum member who has added a video card could look at their settings in BIOS and tell me what to try setting mine to? and should I change the settings/save/power down without booting into Windows, put the new card in, then reboot, or am I missing a step?
I have replaced video cards on two Dell desktops but have not had to change anything in BIOS for either event.
thanks for your feedback-this forum is the best!